release: cut the v10.0.7 release

This commit fixes a bug in View Engine whereby the compiler errorneously
thinks that a method of a component has decorator metadata when that
method is one of those in `Object.prototype`, for example `toString`.

This bug is discovered in v10.0.4 of `@angular/language-service` after
the default bundle format was switched from ES5 to ES2015.

ES5 output:
```js
if (propMetadata[propName]) {
    decorators.push.apply(decorators, __spread(propMetadata[propName]));
}
```

ES2015 output:
```js
if (propMetadata[propName]) {
    decorators.push(...propMetadata[propName]);
}
```

The bug was not discovered in ES5 because the polyfill for the spread
operator happily accepts parameters that do not have the `iterable`
symbol:

```js
function __spread() {
    for (var ar = [], i = 0; i < arguments.length; i++)
        ar = ar.concat(__read(arguments[i]));
    return ar;
}
```

whereas in es2015 it’ll fail since the iterable symbol is not present in
`propMetadata['toString']` which evaluates to a function.

Fixes https://github.com/angular/vscode-ng-language-service/issues/859

PR Close #38292

.circleci/bazel.linux.rc

@@ -19,4 +19,12 @@ build --local_ram_resources=14336
 
 # All build executed remotely should be done using our RBE configuration.
 build:remote --google_default_credentials
+
+# Upload to GCP's Build Status viewer to allow for us to have better viewing of execution/build
+# logs. This is only done on CI as the BES (GCP's Build Status viewer) API requires credentials
+# from service accounts, rather than end user accounts.
+build:remote --bes_backend=buildeventservice.googleapis.com
+build:remote --bes_timeout=30s
+build:remote --bes_results_url="https://source.cloud.google.com/results/invocations/"
+
 build --config=remote

.circleci/config.yml

@@ -32,7 +32,7 @@ var_4_win: &cache_key_win_fallback v7-angular-win-node-12-{{ checksum ".bazelver
 
 # Cache key for the `components-repo-unit-tests` job. **Note** when updating the SHA in the
 # cache keys also update the SHA for the "COMPONENTS_REPO_COMMIT" environment variable.
-var_5: &components_repo_unit_tests_cache_key v7-angular-components-189d98e8b01b33974328255f085de04251d61567
+var_5: &components_repo_unit_tests_cache_key v7-angular-components-f428c00465dfcf8a020237f22532480eedbd2cb6
 var_6: &components_repo_unit_tests_cache_key_fallback v7-angular-components-
 
 # Workspace initially persisted by the `setup` job, and then enhanced by `build-npm-packages` and

.circleci/env.sh

@@ -74,7 +74,7 @@ setPublicVar COMPONENTS_REPO_TMP_DIR "/tmp/angular-components-repo"
 setPublicVar COMPONENTS_REPO_URL "https://github.com/angular/components.git"
 setPublicVar COMPONENTS_REPO_BRANCH "master"
 # **NOTE**: When updating the commit SHA, also update the cache key in the CircleCI `config.yml`.
-setPublicVar COMPONENTS_REPO_COMMIT "189d98e8b01b33974328255f085de04251d61567"
+setPublicVar COMPONENTS_REPO_COMMIT "f428c00465dfcf8a020237f22532480eedbd2cb6"
 
 
 ####################################################################################################

.circleci/trigger-webhook.js

@@ -60,14 +60,15 @@ if (require.resolve === module) {
 
 // Helpers
 function _main(args) {
-  triggerWebhook(...args).
-    then(({statusCode, responseText}) => (200 <= statusCode && statusCode < 400) ?
-      console.log(`Status: ${statusCode}\n${responseText}`) :
-      Promise.reject(new Error(`Request failed (status: ${statusCode}): ${responseText}`))).
-    catch(err => {
-      console.error(err);
-      process.exit(1);
-    });
+  triggerWebhook(...args)
+      .then(
+          ({statusCode, responseText}) => (200 <= statusCode && statusCode < 400) ?
+              console.log(`Status: ${statusCode}\n${responseText}`) :
+              Promise.reject(new Error(`Request failed (status: ${statusCode}): ${responseText}`)))
+      .catch(err => {
+        console.error(err);
+        process.exit(1);
+      });
 }
 
 function postJson(url, data) {
@@ -77,15 +78,12 @@ function postJson(url, data) {
       const statusCode = res.statusCode || -1;
       let responseText = '';
 
-      res.
-        on('error', reject).
-        on('data', d => responseText += d).
-        on('end', () => resolve({statusCode, responseText}));
+      res.on('error', reject)
+          .on('data', d => responseText += d)
+          .on('end', () => resolve({statusCode, responseText}));
     };
 
-    request(url, opts, onResponse).
-      on('error', reject).
-      end(JSON.stringify(data));
+    request(url, opts, onResponse).on('error', reject).end(JSON.stringify(data));
   });
 }
 

.github/angular-robot.yml

@@ -154,6 +154,12 @@ triage:
     -
       - "type: RFC / Discussion / question"
       - "comp: *"
+    -
+      - "type: confusing"
+      - "comp: *"
+    -
+      - "type: use-case"
+      - "comp: *"
 
 # options for the triage PR plugin
 triagePR:

.gitignore

@@ -42,3 +42,6 @@ yarn-error.log
 
 .notes.md
 baseline.json
+
+# Ignore .history for the xyz.local-history VSCode extension
+.history

.gitmessage

@@ -0,0 +1,145 @@
+<type>(<scope>): <summary>
+
+<Describe the motivation behind this change - explain WHY you are making this change. Wrap all lines
+at 100 characters.>
+
+Fixes #<issue number>
+
+# ────────────────────────────────────────── 100 chars ────────────────────────────────────────────┤
+
+
+# Example Commit Messages
+# =======================
+
+
+# ─── Example: Simple refactor ────────────────────────────────────────────────────────────────────┤
+# refactor(core): rename refreshDynamicEmbeddedViews to refreshEmbeddedViews
+#
+# Improve code readability. The original name no longer matches how the function is used.
+# ─────────────────────────────────────────────────────────────────────────────────────────────────┤
+
+
+# ─── Example: Simple docs change ─────────────────────────────────────────────────────────────────┤
+# docs: clarify the service limitation in providers.md guide
+#
+# Fixes #36332
+# ─────────────────────────────────────────────────────────────────────────────────────────────────┤
+
+
+# ─── Example: A bug fix ──────────────────────────────────────────────────────────────────────────┤
+# fix(ngcc): ensure lockfile is removed when `analyzeFn` fails
+#
+# Previously an error thrown in the `analyzeFn` would cause the ngcc process to exit immediately
+# without removing the lockfile, and potentially before the unlocker process had been successfully
+# spawned resulting in the lockfile being orphaned and left behind.
+#
+# Now we catch these errors and remove the lockfile as needed.
+# ─────────────────────────────────────────────────────────────────────────────────────────────────┤
+
+
+# ─── Example: Breaking change ────────────────────────────────────────────────────────────────────┤
+# feat(bazel): simplify ng_package by dropping esm5 and fesm5
+#
+# esm5 and fesm5 distributions are no longer needed and have been deprecated in the past.
+#
+# https://v9.angular.io/guide/deprecations#esm5-and-fesm5-code-formats-in-angular-npm-packages
+#
+# This commit modifies ng_package to no longer distribute these two formats in npm packages built by
+# ng_package (e.g. @angular/core).
+#
+# This commit intentionally doesn't fully clean up the ng_package rule to remove all traces of esm5
+# and fems5 build artifacts as that is a bigger cleanup and currently we are narrowing down the
+# scope of this change to the MVP needed for v10, which in this case is 'do not put esm5 and fesm5'
+# into the npm packages.
+#
+# More cleanup to follow: https://angular-team.atlassian.net/browse/FW-2143
+#
+# BREAKING CHANGE: esm5 and fesm5 format is no longer distributed in Angular's npm packages e.g.
+# @angular/core
+#
+# Angular CLI will automatically downlevel the code to es5 if differential loading is enabled in the
+# Angular project, so no action is required from Angular CLI users.
+#
+# If you are not using Angular CLI to build your application or library, and you need to be able to
+# build es5 artifacts, then you will need to downlevel the distributed Angular code to es5 on your
+# own.
+#
+#
+# Fixes #1234
+# ─────────────────────────────────────────────────────────────────────────────────────────────────┤
+
+
+
+# Angular Commit Message Format
+# =============================
+#
+# The full specification of the Angular Commit Message Format can be found at
+# https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
+#
+# The following is an excerpt of the specification with the most commonly needed info.
+#
+# Each commit message consists of a *header*, a *body*, and a *footer*.
+#
+# <header>
+# <BLANK LINE>
+# <body>
+# <BLANK LINE>
+# <footer>
+#
+# The header is mandatory.
+#
+# The body is mandatory for all commits except for those of scope "docs". When the body is required
+# it must be at least 20 characters long.
+#
+# The footer is optional.
+#
+# Any line of the commit message cannot be longer than 100 characters.
+#
+#
+# Commit Message Header
+# ---------------------
+#
+# <type>(<scope>): <short summary>
+#   │       │             │
+#   │       │             └─⫸ Summary in present tense. Not capitalized. No period at the end.
+#   │       │
+#   │       └─⫸ Commit Scope: animations|bazel|benchpress|common|compiler|compiler-cli|core|
+#   │                          elements|forms|http|language-service|localize|platform-browser|
+#   │                          platform-browser-dynamic|platform-server|platform-webworker|
+#   │                          platform-webworker-dynamic|router|service-worker|upgrade|zone.js|
+#   │                          packaging|changelog|dev-infra|docs-infra|migrations|ngcc|ve
+#   │                          https://github.com/angular/angular/blob/master/CONTRIBUTING.md#scope
+#   │
+#   └─⫸ Commit Type: build|ci|docs|feat|fix|perf|refactor|style|test
+#                     https://github.com/angular/angular/blob/master/CONTRIBUTING.md#type
+#
+#
+# Commit Message Body
+# ---------------------
+#
+# Just as in the summary, use the imperative, present tense: "fix" not "fixed" nor "fixes".
+#
+# Explain the motivation for the change in the commit message body. This commit message should
+# explain WHY you are making the change. You can include a comparison of the previous behavior with
+# the new behavior in order to illustrate the impact of the change.
+#
+#
+# Commit Message Footer
+# ---------------------
+#
+# The footer can contain information about breaking changes and is also the place to reference
+# GitHub issues, Jira tickets, and other PRs that this commit closes or is related to.
+#
+# ```
+# BREAKING CHANGE: <breaking change summary>
+# <BLANK LINE>
+# <breaking change description + migration instructions>
+# <BLANK LINE>
+# <BLANK LINE>
+# Fixes #<issue number>
+# ```
+#
+# Breaking Change section should start with the phrase "BREAKING CHANGE: " followed by a summary of
+# the breaking change, a blank line, and a detailed description of the breaking change that also
+# includes migration instructions.
+#

.ng-dev/commit-message.ts

@@ -0,0 +1,52 @@
+import {CommitMessageConfig} from '../dev-infra/commit-message/config';
+
+/**
+ * The configuration for `ng-dev commit-message` commands.
+ */
+export const commitMessage: CommitMessageConfig = {
+  maxLineLength: 120,
+  minBodyLength: 20,
+  minBodyLengthTypeExcludes: ['docs'],
+  types: [
+    'build',
+    'ci',
+    'docs',
+    'feat',
+    'fix',
+    'perf',
+    'refactor',
+    'release',
+    'style',
+    'test',
+  ],
+  scopes: [
+    'animations',
+    'bazel',
+    'benchpress',
+    'changelog',
+    'common',
+    'compiler',
+    'compiler-cli',
+    'core',
+    'dev-infra',
+    'docs-infra',
+    'elements',
+    'forms',
+    'http',
+    'language-service',
+    'localize',
+    'migrations',
+    'ngcc',
+    'packaging',
+    'platform-browser',
+    'platform-browser-dynamic',
+    'platform-server',
+    'platform-webworker',
+    'platform-webworker-dynamic',
+    'router',
+    'service-worker',
+    'upgrade',
+    've',
+    'zone.js',
+  ]
+};

.ng-dev/config.ts

@@ -1,120 +1,8 @@
-import {MergeConfig} from '../dev-infra/pr/merge/config';
+import {commitMessage} from './commit-message';
+import {format} from './format';
+import {github} from './github';
+import {merge} from './merge';
 
-// The configuration for `ng-dev commit-message` commands.
-const commitMessage = {
-  'maxLength': 120,
-  'minBodyLength': 100,
-  'types': [
-    'build',
-    'ci',
-    'docs',
-    'feat',
-    'fix',
-    'perf',
-    'refactor',
-    'release',
-    'style',
-    'test',
-  ],
-  'scopes': [
-    'animations',
-    'bazel',
-    'benchpress',
-    'changelog',
-    'common',
-    'compiler',
-    'compiler-cli',
-    'core',
-    'dev-infra',
-    'docs-infra',
-    'elements',
-    'forms',
-    'http',
-    'language-service',
-    'localize',
-    'ngcc',
-    'packaging',
-    'platform-browser',
-    'platform-browser-dynamic',
-    'platform-server',
-    'platform-webworker',
-    'platform-webworker-dynamic',
-    'router',
-    'service-worker',
-    'upgrade',
-    've',
-    'zone.js',
-  ]
-};
-
-// The configuration for `ng-dev format` commands.
-const format = {
-  'clang-format': {
-    'matchers': [
-      'dev-infra/**/*.{js,ts}',
-      'packages/**/*.{js,ts}',
-      '!packages/zone.js',
-      '!packages/common/locales/**/*.{js,ts}',
-      '!packages/common/src/i18n/available_locales.ts',
-      '!packages/common/src/i18n/currencies.ts',
-      '!packages/common/src/i18n/locale_en.ts',
-      'modules/benchmarks/**/*.{js,ts}',
-      'modules/playground/**/*.{js,ts}',
-      'tools/**/*.{js,ts}',
-      '!tools/gulp-tasks/cldr/extract.js',
-      '!tools/public_api_guard/**/*.d.ts',
-      '!tools/ts-api-guardian/test/fixtures/**',
-      '*.{js,ts}',
-      '!**/node_modules/**',
-      '!**/dist/**',
-      '!**/built/**',
-      '!shims_for_IE.js',
-    ]
-  },
-  'buildifier': true
-};
-
-/** Github metadata information for `ng-dev` commands. */
-const github = {
-  owner: 'angular',
-  name: 'angular',
-};
-
-// Configuration for the `ng-dev pr merge` command. The command can be used
-// for merging upstream pull requests into branches based on a PR target label.
-const merge = () => {
-  // TODO: resume dynamically determining patch branch
-  const patch = '10.0.x';
-  const config: MergeConfig = {
-    githubApiMerge: false,
-    claSignedLabel: 'cla: yes',
-    mergeReadyLabel: /^PR action: merge(-assistance)?/,
-    commitMessageFixupLabel: 'commit message fixup',
-    labels: [
-      {
-        pattern: 'PR target: master-only',
-        branches: ['master'],
-      },
-      {
-        pattern: 'PR target: patch-only',
-        branches: [patch],
-      },
-      {
-        pattern: 'PR target: master & patch',
-        branches: ['master', patch],
-      },
-    ],
-    requiredBaseCommits: {
-      // PRs that target either `master` or the patch branch, need to be rebased
-      // on top of the latest commit message validation fix.
-      'master': '5aeb9a4124922d8ac08eb73b8f322905a32b0b3a',
-      [patch]: '27b95ba64a5d99757f4042073fd1860e20e3ed24'
-    },
-  };
-  return config;
-};
-
-// Export function to build ng-dev configuration object.
 module.exports = {
   commitMessage,
   format,

.ng-dev/format.ts

@@ -0,0 +1,22 @@
+import {FormatConfig} from '../dev-infra/format/config';
+
+/**
+ * Configuration for the `ng-dev format` command.
+ */
+export const format: FormatConfig = {
+  'clang-format': {
+    'matchers': [
+      '**/*.{js,ts}',
+      // TODO: burn down format failures and remove aio and integration exceptions.
+      '!aio/**',
+      '!integration/**',
+      // Both third_party and .yarn are directories containing copied code which should
+      // not be modified.
+      '!third_party/**',
+      '!.yarn/**',
+      // Do not format d.ts files as they are generated
+      '!**/*.d.ts',
+    ]
+  },
+  'buildifier': true
+};

.ng-dev/gitconfig

@@ -0,0 +1,15 @@
+# The file is inert unless it's explicitly included into the local git config via:
+#
+# ```
+# git config --add include.path '../.ng-dev/gitconfig'
+# ```
+#
+# Calling that command will append the following into `.git/config` of the current git workspace
+# (i.e. $GIT_DIR, typically `angular/.git/config`):
+#
+# ```
+# [include]
+#     path = ../.ng-dev/gitconfig
+# ```
+[commit]
+  template = .gitmessage

.ng-dev/github.ts

@@ -0,0 +1,11 @@
+import {GithubConfig} from '../dev-infra/utils/config';
+
+/**
+ * Github configuration for the `ng-dev` command. This repository is used as
+ * remote for the merge script and other utilities like `ng-dev pr rebase`.
+ */
+
+export const github: GithubConfig = {
+  owner: 'angular',
+  name: 'angular'
+};

.ng-dev/merge.ts

@@ -0,0 +1,38 @@
+import {MergeConfig} from '../dev-infra/pr/merge/config';
+
+/**
+ * Configuration for the merge tool in `ng-dev`. This sets up the labels which
+ * are respected by the merge script (e.g. the target labels).
+ */
+export const merge = (): MergeConfig => {
+  // TODO: resume dynamically determining patch branch
+  const patch = '10.0.x';
+  return {
+    githubApiMerge: false,
+    claSignedLabel: 'cla: yes',
+    mergeReadyLabel: /^PR action: merge(-assistance)?/,
+    caretakerNoteLabel: 'PR action: merge-assistance',
+    commitMessageFixupLabel: 'commit message fixup',
+    labels: [
+      {
+        pattern: 'PR target: master-only',
+        branches: ['master'],
+      },
+      {
+        pattern: 'PR target: patch-only',
+        branches: [patch],
+      },
+      {
+        pattern: 'PR target: master & patch',
+        branches: ['master', patch],
+      },
+    ],
+    requiredBaseCommits: {
+      // PRs that target either `master` or the patch branch, need to be rebased
+      // on top of the latest commit message validation fix.
+      // These SHAs are the commits that update the required license text in the header.
+      'master': '5aeb9a4124922d8ac08eb73b8f322905a32b0b3a',
+      [patch]: '27b95ba64a5d99757f4042073fd1860e20e3ed24'
+    },
+  };
+};

.pullapprove.yml

@@ -34,41 +34,8 @@
 ####################################################################################
 #  GitHub usernames
 ####################################################################################
-#  aikidave - Dave Shevitz
-#  alan-agius4 - Alan Agius
-#  alxhub - Alex Rickabaugh
-#  AndrewKushnir - Andrew Kushnir
-#  andrewseguin - Andrew Seguin
-#  atscott - Andrew Scott
-#  ayazhafiz - Ayaz Hafiz
-#  clydin - Charles Lyding
-#  crisbeto - Kristiyan Kostadinov
-#  dennispbrown - Denny Brown
-#  devversion - Paul Gschwendtner
-#  dgp1130 - Doug Parker
-#  filipesilva - Filipe Silva
-#  gkalpak - Georgios Kalpakas
-#  gregmagolan - Greg Magolan
-#  IgorMinar - Igor Minar
-#  jbogarthyde - Judy Bogart
-#  jelbourn - Jeremy Elbourn
-#  JiaLiPassion - Jia Li
-#  JoostK - Joost Koehoorn
-#  josephperrott - Joey Perrott
-#  juleskremer - Jules Kremer
-#  kapunahelewong - Kapunahele Wong
-#  kara - Kara Erickson
-#  kyliau - Keen Yee Liau
-#  manughub - Manu Murthy
-#  matsko - Matias Niemela
-#  mgechev - Minko Gechev
-#  mhevery - Miško Hevery
-#  michaelprentice - Michael Prentice
-#  mmalerba - Miles Malerba
-#  petebacondarwin - Pete Bacon Darwin
-#  pkozlowski-opensource - Pawel Kozlowski
-#  robwormald - Rob Wormald
-#  StephenFluin - Stephen Fluin
+# See reviewer list under `required-minimum-review` group.  Team member names and
+# usernames are managed there.
 
 
 ####################################################################################
@@ -100,8 +67,35 @@ version: 3
 # Meta field that goes unused by PullApprove to allow for defining aliases to be
 # used throughout the config.
 meta:
-  1: &can-be-global-approved "\"global-approvers\" not in groups.approved"
-  2: &can-be-global-docs-approved "\"global-docs-approvers\" not in groups.approved"
+  # The following groups have no file based conditions and will be initially `active` on all PRs
+  # - `global-approvers`
+  # - `global-docs-approvers`
+  # - `required-minimum-review`
+  #
+  # By checking the number of active/pending/rejected groups when these are excluded, we can determine
+  # if any other groups are matched.
+  #
+  # Note: Because all inactive groups start as pending, we are only checking pending and rejected active groups.
+  #
+  # Also note that the ordering of groups matters in this file. The only groups visible to the current
+  # one are those that appear above it.
+  no-groups-above-this-pending: &no-groups-above-this-pending
+    len(groups.active.pending.exclude("required-minimum-review").exclude("global-approvers").exclude("global-docs-approvers")) == 0
+  no-groups-above-this-rejected: &no-groups-above-this-rejected
+    len(groups.active.rejected.exclude("required-minimum-review").exclude("global-approvers").exclude("global-docs-approvers")) == 0
+  no-groups-above-this-active: &no-groups-above-this-active
+    len(groups.active.exclude("required-minimum-review").exclude("global-approvers").exclude("global-docs-approvers")) == 0
+
+  can-be-global-approved: &can-be-global-approved "\"global-approvers\" not in groups.approved"
+  can-be-global-docs-approved: &can-be-global-docs-approved "\"global-docs-approvers\" not in groups.approved"
+  defaults: &defaults
+    reviews:
+      # Authors provide their approval implicitly, this approval allows for a reviewer
+      # from a group not to need a review specifically for an area of the repository
+      # they own.  This is coupled with the `required-minimum-review` group which requires
+      # that all PRs are reviewed by at least one team member who is not the author of
+      # the PR.
+      author_value: 1
 
 # turn on 'draft' support
 # https://docs.pullapprove.com/config/github-api-version/
@@ -121,6 +115,54 @@ pullapprove_conditions:
 
 
 groups:
+  # =========================================================
+  # Require review on all PRs
+  #
+  # All PRs require at least one review.  This rule will not
+  # request any reviewers, however will require that at least
+  # one review is provided before the group is satisfied.
+  # =========================================================
+  required-minimum-review:
+    reviews:
+      request: 0 # Do not request any reviews from the reviewer group
+      required: 1 # Require that all PRs have approval from at least one of the users in the group
+      author_value: 0 # The author of the PR cannot provide an approval for themself
+    reviewers:
+      users:
+         - aikidave                # Dave Shevitz
+         - alan-agius4             # Alan Agius
+         - alxhub                  # Alex Rickabaugh
+         - AndrewKushnir           # Andrew Kushnir
+         - andrewseguin            # Andrew Seguin
+         - atscott                 # Andrew Scott
+         - ayazhafiz               # Ayaz Hafiz
+         - clydin                  # Charles Lyding
+         - crisbeto                # Kristiyan Kostadinov
+         - dennispbrown            # Denny Brown
+         - devversion              # Paul Gschwendtner
+         - dgp1130                 # Doug Parker
+         - filipesilva             # Filipe Silva
+         - gkalpak                 # Georgios Kalpakas
+         - gregmagolan             # Greg Magolan
+         - IgorMinar               # Igor Minar
+         - jbogarthyde             # Judy Bogart
+         - jelbourn                # Jeremy Elbourn
+         - JiaLiPassion            # Jia Li
+         - JoostK                  # Joost Koehoorn
+         - josephperrott           # Joey Perrott
+         - juleskremer             # Jules Kremer
+         - kapunahelewong          # Kapunahele Wong
+         - kara                    # Kara Erickson
+         - kyliau                  # Keen Yee Liau
+         - manughub                # Manu Murthy
+         - mgechev                 # Minko Gechev
+         - mhevery                 # Miško Hevery
+         - michaelprentice         # Michael Prentice
+         - mmalerba                # Miles Malerba
+         - petebacondarwin         # Pete Bacon Darwin
+         - pkozlowski-opensource   # Pawel Kozlowski
+         - StephenFluin            # Stephen Fluin
+
   # =========================================================
   #  Global Approvers
   #
@@ -161,6 +203,7 @@ groups:
   #  Framework: Animations
   # =========================================================
   fw-animations:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -178,13 +221,16 @@ groups:
           ])
     reviewers:
       users:
-        - matsko
+        - crisbeto
+        - IgorMinar
+        - jelbourn
 
 
   # =========================================================
   #  Framework: Compiler
   # =========================================================
   fw-compiler:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -209,6 +255,7 @@ groups:
   #  Framework: Compiler / ngcc
   # =========================================================
   fw-ngcc:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -225,6 +272,7 @@ groups:
   #  Framework: Migrations
   # =========================================================
   fw-migrations:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -240,6 +288,7 @@ groups:
   #  Framework: Core
   # =========================================================
   fw-core:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -313,26 +362,38 @@ groups:
           'aio/content/guide/ngmodule-vs-jsmodule.md',
           'aio/content/guide/module-types.md',
           'aio/content/guide/template-syntax.md',
+          'aio/content/guide/built-in-template-functions.md',
           'aio/content/examples/built-in-template-functions/**',
+          'aio/content/guide/event-binding.md',
           'aio/content/examples/event-binding/**',
+          'aio/content/guide/interpolation.md',
           'aio/content/examples/interpolation/**',
           'aio/content/examples/template-syntax/**',
           'aio/content/images/guide/template-syntax/**',
+          'aio/content/guide/binding-syntax.md',
           'aio/content/examples/binding-syntax/**',
+          'aio/content/guide/property-binding.md',
           'aio/content/examples/property-binding/**',
+          'aio/content/guide/attribute-binding.md',
           'aio/content/examples/attribute-binding/**',
+          'aio/content/guide/two-way-binding.md',
           'aio/content/examples/two-way-binding/**',
+          'aio/content/guide/built-in-directives.md',
           'aio/content/examples/built-in-directives/**',
           'aio/content/images/guide/built-in-directives/**',
+          'aio/content/guide/template-reference-variables.md',
           'aio/content/examples/template-reference-variables/**',
+          'aio/content/guide/inputs-outputs.md',
           'aio/content/examples/inputs-outputs/**',
           'aio/content/images/guide/inputs-outputs/**',
+          'aio/content/guide/template-expression-operators.md',
           'aio/content/examples/template-expression-operators/**',
           'aio/content/guide/pipes.md',
           'aio/content/examples/pipes/**',
           'aio/content/images/guide/pipes/**',
           'aio/content/guide/providers.md',
           'aio/content/examples/providers/**',
+          'aio/content/images/guide/providers/**',
           'aio/content/guide/singleton-services.md',
           'aio/content/guide/set-document-title.md',
           'aio/content/examples/set-document-title/**',
@@ -340,7 +401,9 @@ groups:
           'aio/content/guide/sharing-ngmodules.md',
           'aio/content/guide/structural-directives.md',
           'aio/content/examples/structural-directives/**',
+          'aio/content/guide/svg-in-templates.md',
           'aio/content/images/guide/structural-directives/**',
+          'aio/content/guide/template-statements.md',
           'aio/content/guide/user-input.md',
           'aio/content/examples/user-input/**',
           'aio/content/images/guide/user-input/**'
@@ -359,6 +422,7 @@ groups:
   #  Framework: Http
   # =========================================================
   fw-http:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -380,6 +444,7 @@ groups:
   #  Framework: Elements
   # =========================================================
   fw-elements:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -400,6 +465,7 @@ groups:
   #  Framework: Forms
   # =========================================================
   fw-forms:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -432,6 +498,7 @@ groups:
   #  Framework: i18n
   # =========================================================
   fw-i18n:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -465,6 +532,7 @@ groups:
   #  Framework: Platform Server
   # =========================================================
   fw-platform-server:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -484,6 +552,7 @@ groups:
   #  Framework: Router
   # =========================================================
   fw-router:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -493,6 +562,7 @@ groups:
           'packages/examples/router/**',
           'aio/content/guide/router.md',
           'aio/content/guide/router-tutorial.md',
+          'aio/content/guide/router-tutorial-toh.md',
           'aio/content/examples/router-tutorial/**',
           'aio/content/examples/router/**',
           'aio/content/images/guide/router/**'
@@ -506,6 +576,7 @@ groups:
   #  Framework: Service Worker
   # =========================================================
   fw-service-worker:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -533,6 +604,7 @@ groups:
   #  Framework: Upgrade
   # =========================================================
   fw-upgrade:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -563,6 +635,7 @@ groups:
   #  Framework: Testing
   # =========================================================
   fw-testing:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -570,6 +643,14 @@ groups:
         contains_any_globs(files.exclude('packages/compiler-cli/**'), [
           '**/testing/**',
           'aio/content/guide/testing.md',
+          'aio/content/guide/test-debugging.md',
+          'aio/content/guide/testing-attribute-directives.md',
+          'aio/content/guide/testing-code-coverage.md',
+          'aio/content/guide/testing-components-basics.md',
+          'aio/content/guide/testing-components-scenarios.md',
+          'aio/content/guide/testing-pipes.md',
+          'aio/content/guide/testing-services.md',
+          'aio/content/guide/testing-utility-apis.md',
           'aio/content/examples/testing/**',
           'aio/content/images/guide/testing/**'
           ])
@@ -584,6 +665,7 @@ groups:
   #  Framework: Benchmarks
   # =========================================================
   fw-benchmarks:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - >
@@ -600,6 +682,7 @@ groups:
   #  Framework: Playground
   # =========================================================
   fw-playground:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - >
@@ -617,6 +700,7 @@ groups:
   #  Framework: Security
   # =========================================================
   fw-security:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -646,6 +730,7 @@ groups:
   #  Bazel
   # =========================================================
   bazel:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -664,6 +749,7 @@ groups:
   #  Language Service
   # =========================================================
   language-service:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -683,6 +769,7 @@ groups:
   #  zone.js
   # =========================================================
   zone-js:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -701,6 +788,7 @@ groups:
   #  Benchpress
   # =========================================================
   benchpress:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -718,6 +806,7 @@ groups:
   #  Integration Tests
   # =========================================================
   integration-tests:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - >
@@ -735,6 +824,7 @@ groups:
   #  Docs: Gettings Started & Tutorial
   # =========================================================
   docs-getting-started-and-tutorial:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -767,6 +857,7 @@ groups:
   #  Docs: Marketing
   # =========================================================
   docs-marketing:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -789,6 +880,7 @@ groups:
   #  Docs: Observables
   # =========================================================
   docs-observables:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -814,6 +906,7 @@ groups:
   #  Docs: Packaging, Tooling, Releasing
   # =========================================================
   docs-packaging-and-releasing:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -833,7 +926,7 @@ groups:
           'aio/content/guide/migration-localize.md',
           'aio/content/guide/migration-module-with-providers.md',
           'aio/content/guide/static-query-migration.md',
-          'aio/content/guide/updating-to-version-9.md',
+          'aio/content/guide/updating-to-version-10.md',
           'aio/content/guide/ivy-compatibility.md',
           'aio/content/guide/ivy-compatibility-examples.md'
           ])
@@ -873,6 +966,7 @@ groups:
   #  Docs: CLI
   # =========================================================
   docs-cli:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -889,8 +983,12 @@ groups:
           'aio/content/images/guide/deployment/**',
           'aio/content/guide/file-structure.md',
           'aio/content/guide/ivy.md',
+          'aio/content/guide/strict-mode.md',
           'aio/content/guide/web-worker.md',
           'aio/content/guide/workspace-config.md',
+          'aio/content/guide/migration-solution-style-tsconfig.md',
+          'aio/content/guide/migration-update-module-and-target-compiler-options.md',
+          'aio/content/guide/migration-update-libraries-tslib.md',
           ])
     reviewers:
       users:
@@ -903,6 +1001,7 @@ groups:
   #  Docs: CLI Libraries
   # =========================================================
   docs-libraries:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -923,6 +1022,7 @@ groups:
   #  Docs: Schematics
   # =========================================================
   docs-schematics:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -945,6 +1045,7 @@ groups:
   #  Docs-infra
   # =========================================================
   docs-infra:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - *can-be-global-docs-approved
@@ -974,10 +1075,11 @@ groups:
   #  Dev-infra
   # =========================================================
   dev-infra:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - >
-        contains_any_globs(files.exclude("CHANGELOG.md"), [
+        contains_any_globs(files.exclude("CHANGELOG.md").exclude("packages/compiler-cli/**/BUILD.bazel"), [
           '*',
           '.circleci/**',
           '.devcontainer/**',
@@ -1009,7 +1111,6 @@ groups:
           'tools/circular_dependency_test/**',
           'tools/contributing-stats/**',
           'tools/gulp-tasks/**',
-          'tools/ngcontainer/**',
           'tools/npm/**',
           'tools/npm_integration_test/**',
           'tools/rxjs/**',
@@ -1039,7 +1140,10 @@ groups:
   #  Public API
   # =========================================================
   public-api:
+    <<: *defaults
     conditions:
+      - *no-groups-above-this-pending
+      - *no-groups-above-this-rejected
       - *can-be-global-approved
       - >
         contains_any_globs(files, [
@@ -1053,13 +1157,16 @@ groups:
           ])
     reviewers:
       users:
-        - alxhub
+        - AndrewKushnir
         - IgorMinar
+        - alxhub
+        - atscott
         - jelbourn
+        - petebacondarwin
         - pkozlowski-opensource
     reviews:
-      request: -1   # request reviews from everyone
-      required: 3   # require at least 3 approvals
+      request: 4 # Request reviews from four people
+      required: 3 # Require that three people approve
       reviewed_for: required
 
 
@@ -1067,7 +1174,10 @@ groups:
   #  Size tracking
   # ================================================
   size-tracking:
+    <<: *defaults
     conditions:
+      - *no-groups-above-this-pending
+      - *no-groups-above-this-rejected
       - *can-be-global-approved
       - >
         contains_any_globs(files, [
@@ -1075,13 +1185,16 @@ groups:
           ])
     reviewers:
       users:
-        - alxhub
+        - AndrewKushnir
         - IgorMinar
+        - alxhub
+        - atscott
         - jelbourn
+        - petebacondarwin
         - pkozlowski-opensource
     reviews:
-      request: -1   # request reviews from everyone
-      required: 2   # require at least 2 approvals
+      request: 4 # Request reviews from four people
+      required: 2 # Require that two people approve
       reviewed_for: required
 
 
@@ -1089,7 +1202,10 @@ groups:
   #  Circular dependencies
   # ================================================
   circular-dependencies:
+    <<: *defaults
     conditions:
+      - *no-groups-above-this-pending
+      - *no-groups-above-this-rejected
       - *can-be-global-approved
       - >
         contains_any_globs(files, [
@@ -1097,9 +1213,12 @@ groups:
         ])
     reviewers:
       users:
+        - AndrewKushnir
         - IgorMinar
+        - alxhub
+        - atscott
         - jelbourn
-        - josephperrott
+        - petebacondarwin
         - pkozlowski-opensource
 
 
@@ -1111,6 +1230,7 @@ groups:
   #  Code Ownership
   # =========================================================
   code-ownership:
+    <<: *defaults
     conditions:
       - *can-be-global-approved
       - >
@@ -1119,13 +1239,20 @@ groups:
           ])
     reviewers:
       users:
+        - AndrewKushnir
         - IgorMinar
+        - alxhub
+        - atscott
+        - jelbourn
+        - josephperrott
+        - mhevery
 
 
   # ====================================================
   #  Catch all for if no groups match the code change
   # ====================================================
   fallback:
+    <<: *defaults
     # A group is considered to be `active` for a PR if at least one of group's
     # conditions matches the PR.
     #
@@ -1145,13 +1272,10 @@ groups:
     # `global-approvers` can still approve PRs that match this `fallback` rule,
     # but that should be an exception and not an expectation.
     conditions:
+      - *no-groups-above-this-active
+      # When any of the `global-*` groups is approved, they cause other groups to deactivate.
+      # In those cases, the condition above would evaluate to `true` while in reality, only a global
+      # approval has been provided. To ensure we don't activate the fallback group in such cases,
+      # ensure that no explicit global approval has been provided.
       - *can-be-global-approved
-      # The following groups have no conditions and will be `active` on all PRs
-      # - `global-approvers`
-      # - `global-docs-approvers`
-      #
-      # Since this means the minimum number of active groups a PR can have is 2, this
-      # `fallback` group should be matched anytime the number of active groups is at or
-      # below this minimum.  This work as a protection to ensure that pullapprove does
-      # not incidently mark a PR as passing without meeting the review criteria.
-      - len(groups.active) <= 2
+      - *can-be-global-docs-approved

.vscode/recommended-settings.json

@@ -26,6 +26,7 @@
     "**/bazel-out": true,
     "**/dist": true,
     "**/aio/src/generated": true,
+    ".history": true,
   },
   "git.ignoreLimitWarning": true,
-}
+}

BUILD.bazel

@@ -24,7 +24,7 @@ filegroup(
         "//packages/zone.js/dist:zone-testing.js",
         "//packages/zone.js/dist:task-tracking.js",
         "//:test-events.js",
-        "//:shims_for_IE.js",
+        "//:third_party/shims_for_IE.js",
         # Including systemjs because it defines `__eval`, which produces correct stack traces.
         "@npm//:node_modules/systemjs/dist/system.src.js",
         "@npm//:node_modules/reflect-metadata/Reflect.js",

CONTRIBUTING.md

@@ -1,7 +1,7 @@
 # Contributing to Angular
 
-We would love for you to contribute to Angular and help make it even better than it is
-today! As a contributor, here are the guidelines we would like you to follow:
+We would love for you to contribute to Angular and help make it even better than it is today!
+As a contributor, here are the guidelines we would like you to follow:
 
  - [Code of Conduct](#coc)
  - [Question or Problem?](#question)
@@ -12,50 +12,63 @@ today! As a contributor, here are the guidelines we would like you to follow:
  - [Commit Message Guidelines](#commit)
  - [Signing the CLA](#cla)
 
+
 ## <a name="coc"></a> Code of Conduct
-Help us keep Angular open and inclusive. Please read and follow our [Code of Conduct][coc].
+
+Help us keep Angular open and inclusive.
+Please read and follow our [Code of Conduct][coc].
+
 
 ## <a name="question"></a> Got a Question or Problem?
 
-Do not open issues for general support questions as we want to keep GitHub issues for bug reports and feature requests. You've got much better chances of getting your question answered on [Stack Overflow](https://stackoverflow.com/questions/tagged/angular) where the questions should be tagged with tag `angular`.
+Do not open issues for general support questions as we want to keep GitHub issues for bug reports and feature requests.
+Instead, we recommend using [Stack Overflow](https://stackoverflow.com/questions/tagged/angular) to ask support-related questions. When creating a new question on Stack Overflow, make sure to add the `angular` tag.
 
 Stack Overflow is a much better place to ask questions since:
 
 - there are thousands of people willing to help on Stack Overflow
-- questions and answers stay available for public viewing so your question / answer might help someone else
+- questions and answers stay available for public viewing so your question/answer might help someone else
 - Stack Overflow's voting system assures that the best answers are prominently visible.
 
 To save your and our time, we will systematically close all issues that are requests for general support and redirect people to Stack Overflow.
 
 If you would like to chat about the question in real-time, you can reach out via [our gitter channel][gitter].
 
+
 ## <a name="issue"></a> Found a Bug?
-If you find a bug in the source code, you can help us by
-[submitting an issue](#submit-issue) to our [GitHub Repository][github]. Even better, you can
-[submit a Pull Request](#submit-pr) with a fix.
+
+If you find a bug in the source code, you can help us by [submitting an issue](#submit-issue) to our [GitHub Repository][github].
+Even better, you can [submit a Pull Request](#submit-pr) with a fix.
+
 
 ## <a name="feature"></a> Missing a Feature?
-You can *request* a new feature by [submitting an issue](#submit-issue) to our GitHub
-Repository. If you would like to *implement* a new feature, please submit an issue with
-a proposal for your work first, to be sure that we can use it.
-Please consider what kind of change it is:
+You can *request* a new feature by [submitting an issue](#submit-issue) to our GitHub Repository.
+If you would like to *implement* a new feature, please consider the size of the change in order to determine the right steps to proceed:
+
+* For a **Major Feature**, first open an issue and outline your proposal so that it can be discussed.
+  This process allows us to better coordinate our efforts, prevent duplication of work, and help you to craft the change so that it is successfully accepted into the project.
+
+  **Note**: Adding a new topic to the documentation, or significantly re-writing a topic, counts as a major feature.
 
-* For a **Major Feature**, first open an issue and outline your proposal so that it can be
-discussed. This will also allow us to better coordinate our efforts, prevent duplication of work,
-and help you to craft the change so that it is successfully accepted into the project.
 * **Small Features** can be crafted and directly [submitted as a Pull Request](#submit-pr).
 
+
 ## <a name="submit"></a> Submission Guidelines
 
+
 ### <a name="submit-issue"></a> Submitting an Issue
 
 Before you submit an issue, please search the issue tracker, maybe an issue for your problem already exists and the discussion might inform you of workarounds readily available.
 
-We want to fix all the issues as soon as possible, but before fixing a bug we need to reproduce and confirm it. In order to reproduce bugs, we will systematically ask you to provide a minimal reproduction. Having a minimal reproducible scenario gives us a wealth of important information without going back & forth to you with additional questions.
+We want to fix all the issues as soon as possible, but before fixing a bug we need to reproduce and confirm it.
+In order to reproduce bugs, we require that you provide a minimal reproduction.
+Having a minimal reproducible scenario gives us a wealth of important information without going back and forth to you with additional questions.
 
 A minimal reproduction allows us to quickly confirm a bug (or point out a coding problem) as well as confirm that we are fixing the right problem.
 
-We will be insisting on a minimal reproduction scenario in order to save maintainers time and ultimately be able to fix more bugs. Interestingly, from our experience, users often find coding problems themselves while preparing a minimal reproduction. We understand that sometimes it might be hard to extract essential bits of code from a larger codebase but we really need to isolate the problem before we can fix it.
+We require a minimal reproduction to save maintainers' time and ultimately be able to fix more bugs.
+Often, developers find coding problems themselves while preparing a minimal reproduction.
+We understand that sometimes it might be hard to extract essential bits of code from a larger codebase but we really need to isolate the problem before we can fix it.
 
 Unfortunately, we are not able to investigate / fix bugs without a minimal reproduction, so if we don't hear back from you, we are going to close an issue that doesn't have enough info to be reproduced.
 
@@ -63,57 +76,66 @@ You can file new issues by selecting from our [new issue templates](https://gith
 
 
 ### <a name="submit-pr"></a> Submitting a Pull Request (PR)
+
 Before you submit your Pull Request (PR) consider the following guidelines:
 
-1. Search [GitHub](https://github.com/angular/angular/pulls) for an open or closed PR
-  that relates to your submission. You don't want to duplicate effort.
-1. Be sure that an issue describes the problem you're fixing, or documents the design for the feature you'd like to add.
-  Discussing the design up front helps to ensure that we're ready to accept your work.
-1. Please sign our [Contributor License Agreement (CLA)](#cla) before sending PRs.
-  We cannot accept code without this. Make sure you sign with the primary email address of the Git identity that has been granted access to the Angular repository.
-1. Fork the angular/angular repo.
-1. Make your changes in a new git branch:
+1. Search [GitHub](https://github.com/angular/angular/pulls) for an open or closed PR that relates to your submission.
+   You don't want to duplicate existing efforts.
+
+2. Be sure that an issue describes the problem you're fixing, or documents the design for the feature you'd like to add.
+   Discussing the design upfront helps to ensure that we're ready to accept your work.
+
+3. Please sign our [Contributor License Agreement (CLA)](#cla) before sending PRs.
+   We cannot accept code without a signed CLA.
+   Make sure you author all contributed Git commits with email address associated with your CLA signature.
+
+4. Fork the angular/angular repo.
+
+5. Make your changes in a new git branch:
 
      ```shell
      git checkout -b my-fix-branch master
      ```
 
-1. Create your patch, **including appropriate test cases**.
-1. Follow our [Coding Rules](#rules).
-1. Run the full Angular test suite, as described in the [developer documentation][dev-doc],
-  and ensure that all tests pass.
-1. Commit your changes using a descriptive commit message that follows our
-  [commit message conventions](#commit). Adherence to these conventions
-  is necessary because release notes are automatically generated from these messages.
+6. Create your patch, **including appropriate test cases**.
+
+7. Follow our [Coding Rules](#rules).
+
+8. Run the full Angular test suite, as described in the [developer documentation][dev-doc], and ensure that all tests pass.
+
+9. Commit your changes using a descriptive commit message that follows our [commit message conventions](#commit).
+   Adherence to these conventions is necessary because release notes are automatically generated from these messages.
 
      ```shell
      git commit -a
      ```
     Note: the optional commit `-a` command line option will automatically "add" and "rm" edited files.
 
-1. Push your branch to GitHub:
+10. Push your branch to GitHub:
 
     ```shell
     git push origin my-fix-branch
     ```
 
-1. In GitHub, send a pull request to `angular:master`.
-* If we suggest changes then:
-  * Make the required updates.
-  * Re-run the Angular test suites to ensure tests are still passing.
-  * Rebase your branch and force push to your GitHub repository (this will update your Pull Request):
+11. In GitHub, send a pull request to `angular:master`.
 
-    ```shell
-    git rebase master -i
-    git push -f
-    ```
+   If we ask for changes via code reviews then:
+
+   * Make the required updates.
+   * Re-run the Angular test suites to ensure tests are still passing.
+   * Rebase your branch and force push to your GitHub repository (this will update your Pull Request):
+
+      ```shell
+      git rebase master -i
+      git push -f
+      ```
 
 That's it! Thank you for your contribution!
 
+
 #### After your pull request is merged
 
-After your pull request is merged, you can safely delete your branch and pull the changes
-from the main (upstream) repository:
+After your pull request is merged, you can safely delete your branch and pull the changes from the main (upstream) repository:
 
 * Delete the remote branch on GitHub either through the GitHub web UI or your local shell as follows:
 
@@ -139,55 +161,66 @@ from the main (upstream) repository:
     git pull --ff upstream master
     ```
 
+
 ## <a name="rules"></a> Coding Rules
 To ensure consistency throughout the source code, keep these rules in mind as you are working:
 
 * All features or bug fixes **must be tested** by one or more specs (unit-tests).
-* All public API methods **must be documented**. (Details TBC).
-* We follow [Google's JavaScript Style Guide][js-style-guide], but wrap all code at
-  **100 characters**. An automated formatter is available, see
-  [DEVELOPER.md](docs/DEVELOPER.md#clang-format).
+* All public API methods **must be documented**.
+* We follow [Google's JavaScript Style Guide][js-style-guide], but wrap all code at **100 characters**.
 
-## <a name="commit"></a> Commit Message Guidelines
+   An automated formatter is available, see [DEVELOPER.md](docs/DEVELOPER.md#clang-format).
 
-We have very precise rules over how our git commit messages can be formatted.  This leads to **more
-readable messages** that are easy to follow when looking through the **project history**.  But also,
-we use the git commit messages to **generate the Angular change log**.
 
-### Commit Message Format
-Each commit message consists of a **header**, a **body** and a **footer**.  The header has a special
-format that includes a **type**, a **scope** and a **subject**:
+## <a name="commit"></a> Commit Message Format
+
+*This specification is inspired and supersedes the [AngularJS commit message format][commit-message-format].*
+
+We have very precise rules over how our Git commit messages must be formatted.
+This format leads to **easier to read commit history**.
+
+Each commit message consists of a **header**, a **body**, and a **footer**.
+
 
 ```
-<type>(<scope>): <subject>
+<header>
 <BLANK LINE>
 <body>
 <BLANK LINE>
 <footer>
 ```
 
-The **header** is mandatory and the **scope** of the header is optional.
+The `header` is mandatory and must conform to the [Commit Message Header](#commit-header) format.
 
-Any line of the commit message cannot be longer than 100 characters! This allows the message to be easier
-to read on GitHub as well as in various git tools.
+The `body` is mandatory for all commits except for those of scope "docs".
+When the body is required it must be at least 20 characters long.
 
-The footer should contain a [closing reference to an issue](https://help.github.com/articles/closing-issues-via-commit-messages/) if any.
+The `footer` is optional.
 
-Samples: (even more [samples](https://github.com/angular/angular/commits/master))
+Any line of the commit message cannot be longer than 100 characters.
+
+
+#### <a href="commit-header"></a>Commit Message Header
 
 ```
-docs(changelog): update changelog to beta.5
-```
-```
-fix(release): need to depend on latest rxjs and zone.js
-
-The version in our package.json gets copied to the one we publish, and users need the latest of these.
+<type>(<scope>): <short summary>
+  │       │             │
+  │       │             └─⫸ Summary in present tense. Not capitalized. No period at the end.
+  │       │
+  │       └─⫸ Commit Scope: animations|bazel|benchpress|common|compiler|compiler-cli|core|
+  │                          elements|forms|http|language-service|localize|platform-browser|
+  │                          platform-browser-dynamic|platform-server|platform-webworker|
+  │                          platform-webworker-dynamic|router|service-worker|upgrade|zone.js|
+  │                          packaging|changelog|dev-infra|docs-infra|migrations|ngcc|ve
+  │
+  └─⫸ Commit Type: build|ci|docs|feat|fix|perf|refactor|style|test
 ```
 
-### Revert
-If the commit reverts a previous commit, it should begin with `revert: `, followed by the header of the reverted commit. In the body it should say: `This reverts commit <hash>.`, where the hash is the SHA of the commit being reverted.
+The `<type>` and `<summary>` fields are mandatory, the `(<scope>)` field is optional.
+
+
+##### Type
 
-### Type
 Must be one of the following:
 
 * **build**: Changes that affect the build system or external dependencies (example scopes: gulp, broccoli, npm)
@@ -200,66 +233,95 @@ Must be one of the following:
 * **style**: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
 * **test**: Adding missing tests or correcting existing tests
 
-### Scope
+
+##### Scope
 The scope should be the name of the npm package affected (as perceived by the person reading the changelog generated from commit messages).
 
 The following is the list of supported scopes:
 
-* **animations**
-* **bazel**
-* **benchpress**
-* **common**
-* **compiler**
-* **compiler-cli**
-* **core**
-* **elements**
-* **forms**
-* **http**
-* **language-service**
-* **localize**
-* **platform-browser**
-* **platform-browser-dynamic**
-* **platform-server**
-* **platform-webworker**
-* **platform-webworker-dynamic**
-* **router**
-* **service-worker**
-* **upgrade**
-* **zone.js**
+* `animations`
+* `bazel`
+* `benchpress`
+* `common`
+* `compiler`
+* `compiler-cli`
+* `core`
+* `elements`
+* `forms`
+* `http`
+* `language-service`
+* `localize`
+* `platform-browser`
+* `platform-browser-dynamic`
+* `platform-server`
+* `platform-webworker`
+* `platform-webworker-dynamic`
+* `router`
+* `service-worker`
+* `upgrade`
+* `zone.js`
 
 There are currently a few exceptions to the "use package name" rule:
 
-* **packaging**: used for changes that change the npm package layout in all of our packages, e.g.
-  public path changes, package.json changes done to all packages, d.ts file/format changes, changes
-  to bundles, etc.
-* **changelog**: used for updating the release notes in CHANGELOG.md
-* **docs-infra**: used for docs-app (angular.io) related changes within the /aio directory of the
-  repo
-* **dev-infra**: used for dev-infra related changes within the directories /scripts, /tools and /dev-infra
-* **ngcc**: used for changes to the [Angular Compatibility Compiler](./packages/compiler-cli/ngcc/README.md)
-* **ve**: used for changes specific to ViewEngine (legacy compiler/renderer).
-* none/empty string: useful for `style`, `test` and `refactor` changes that are done across all
-  packages (e.g. `style: add missing semicolons`) and for docs changes that are not related to a
-  specific package (e.g. `docs: fix typo in tutorial`).
+* `packaging`: used for changes that change the npm package layout in all of our packages, e.g. public path changes, package.json changes done to all packages, d.ts file/format changes, changes to bundles, etc.
 
-### Subject
-The subject contains a succinct description of the change:
+* `changelog`: used for updating the release notes in CHANGELOG.md
+
+* `dev-infra`: used for dev-infra related changes within the directories /scripts, /tools and /dev-infra
+
+* `docs-infra`: used for docs-app (angular.io) related changes within the /aio directory of the repo
+
+* `migrations`: used for changes to the `ng update` migrations.
+
+* `ngcc`: used for changes to the [Angular Compatibility Compiler](./packages/compiler-cli/ngcc/README.md)
+
+* `ve`: used for changes specific to ViewEngine (legacy compiler/renderer).
+
+* none/empty string: useful for `style`, `test` and `refactor` changes that are done across all packages (e.g. `style: add missing semicolons`) and for docs changes that are not related to a specific package (e.g. `docs: fix typo in tutorial`).
+
+
+##### Summary
+
+Use the summary field to provide a succinct description of the change:
 
 * use the imperative, present tense: "change" not "changed" nor "changes"
 * don't capitalize the first letter
 * no dot (.) at the end
 
-### Body
-Just as in the **subject**, use the imperative, present tense: "change" not "changed" nor "changes".
-The body should include the motivation for the change and contrast this with previous behavior.
 
-### Footer
-The footer should contain any information about **Breaking Changes** and is also the place to
-reference GitHub issues that this commit **Closes**.
+#### Commit Message Body
 
-**Breaking Changes** should start with the word `BREAKING CHANGE:` with a space or two newlines. The rest of the commit message is then used for this.
+Just as in the summary, use the imperative, present tense: "fix" not "fixed" nor "fixes".
+
+Explain the motivation for the change in the commit message body. This commit message should explain _why_ you are making the change.
+You can include a comparison of the previous behavior with the new behavior in order to illustrate the impact of the change.
+
+
+#### Commit Message Footer
+
+The footer can contain information about breaking changes and is also the place to reference GitHub issues, Jira tickets, and other PRs that this commit closes or is related to.
+
+```
+BREAKING CHANGE: <breaking change summary>
+<BLANK LINE>
+<breaking change description + migration instructions>
+<BLANK LINE>
+<BLANK LINE>
+Fixes #<issue number>
+```
+
+Breaking Change section should start with the phrase "BREAKING CHANGE: " followed by a summary of the breaking change, a blank line, and a detailed description of the breaking change that also includes migration instructions.
+
+
+### Revert commits
+
+If the commit reverts a previous commit, it should begin with `revert: `, followed by the header of the reverted commit.
+
+The content of the commit message body should contain:
+
+- information about the SHA of the commit being reverted in the following format: `This reverts commit <SHA>`,
+- a clear description of the reason for reverting the commit message.
 
-A detailed explanation can be found in this [document][commit-message-format].
 
 ## <a name="cla"></a> Signing the CLA
 
@@ -270,18 +332,17 @@ changes to be accepted, the CLA must be signed. It's a quick process, we promise
 * For corporations, we'll need you to
   [print, sign and one of scan+email, fax or mail the form][corporate-cla].
 
-<hr>
+If you have more than one GitHub accounts, or multiple email addresses associated with a single GitHub account, you must sign the CLA using the primary email address of the GitHub account used to author Git commits and send pull requests.
 
-  If you have more than one Git identity, you must make sure that you sign the CLA using the primary email address associated with the ID that has been granted access to the Angular repository. Git identities can be associated with more than one email address, and only one is primary. Here are some links to help you sort out multiple Git identities and email addresses:
+The following documents can help you sort out issues with GitHub accounts and multiple email addresses:
 
   * https://help.github.com/articles/setting-your-commit-email-address-in-git/
   * https://stackoverflow.com/questions/37245303/what-does-usera-committed-with-userb-13-days-ago-on-github-mean
   * https://help.github.com/articles/about-commit-email-addresses/
   * https://help.github.com/articles/blocking-command-line-pushes-that-expose-your-personal-email-address/
 
-  Note that if you have more than one Git identity, it is important to verify that you are logged in with the same ID with which you signed the CLA, before you commit changes. If not, your PR will fail the CLA check.
 
-<hr>
+
 
 [angular-group]: https://groups.google.com/forum/#!forum/angular
 [coc]: https://github.com/angular/code-of-conduct/blob/master/CODE_OF_CONDUCT.md

aio/angular.json

@@ -58,7 +58,7 @@
               }
             ],
             "styles": [
-              "src/styles.scss"
+              "src/styles/main.scss"
             ],
             "scripts": [],
             "budgets": [
@@ -158,7 +158,7 @@
               }
             ],
             "styles": [
-              "src/styles.scss"
+              "src/styles/main.scss"
             ],
             "scripts": []
           }
@@ -193,4 +193,4 @@
     }
   },
   "defaultProject": "site"
-}
+}

aio/content/cli/index.md

@@ -1,6 +1,6 @@
 # CLI Overview and Command Reference
 
-The Angular CLI is a command-line interface tool that you use to initialize, develop, scaffold, and maintain Angular applications. You can use the tool directly in a command shell, or indirectly through an interactive UI such as [Angular Console](https://angularconsole.com).
+The Angular CLI is a command-line interface tool that you use to initialize, develop, scaffold, and maintain Angular applications directly from a command shell.
 
 ## Installing Angular CLI
 

aio/content/examples/.gitignore

@@ -18,6 +18,7 @@
 **/src/karma.conf.js
 **/.angular-cli.json
 **/.editorconfig
+**/.gitignore
 **/angular.json
 **/tsconfig.json
 **/bs-config.e2e.json

aio/content/examples/animations/src/app/animations.ts

@@ -32,15 +32,15 @@ export const slideInAnimation =
 // #enddocregion style-view
 // #docregion query
       query(':enter', [
-        style({ left: '-100%'})
+        style({ left: '-100%' })
       ]),
       query(':leave', animateChild()),
       group([
         query(':leave', [
-          animate('300ms ease-out', style({ left: '100%'}))
+          animate('300ms ease-out', style({ left: '100%' }))
         ]),
         query(':enter', [
-          animate('300ms ease-out', style({ left: '0%'}))
+          animate('300ms ease-out', style({ left: '0%' }))
         ])
       ]),
       query(':enter', animateChild()),
@@ -56,15 +56,15 @@ export const slideInAnimation =
         })
       ]),
       query(':enter', [
-        style({ left: '-100%'})
+        style({ left: '-100%' })
       ]),
       query(':leave', animateChild()),
       group([
         query(':leave', [
-          animate('200ms ease-out', style({ left: '100%'}))
+          animate('200ms ease-out', style({ left: '100%' }))
         ]),
         query(':enter', [
-          animate('300ms ease-out', style({ left: '0%'}))
+          animate('300ms ease-out', style({ left: '0%' }))
         ])
       ]),
       query(':enter', animateChild()),

aio/content/examples/animations/src/app/app.component.html

@@ -17,7 +17,7 @@ Toggle All Animations <input type="checkbox" [checked]="!animationsDisabled" (cl
 </nav>
 
 <!-- #docregion route-animations-outlet -->
-<div [@routeAnimations]="prepareRoute(outlet)" >
+<div [@routeAnimations]="prepareRoute(outlet)">
   <router-outlet #outlet="outlet"></router-outlet>
 </div>
 <!-- #enddocregion route-animations-outlet -->

aio/content/examples/http/src/app/config/config.service.ts

@@ -76,15 +76,15 @@ export class ConfigService {
       console.error('An error occurred:', error.error.message);
     } else {
       // The backend returned an unsuccessful response code.
-      // The response body may contain clues as to what went wrong,
+      // The response body may contain clues as to what went wrong.
       console.error(
         `Backend returned code ${error.status}, ` +
         `body was: ${error.error}`);
     }
-    // return an observable with a user-facing error message
+    // Return an observable with a user-facing error message.
     return throwError(
       'Something bad happened; please try again later.');
-  };
+  }
   // #enddocregion handleError
 
   makeIntentionalError() {

aio/content/examples/i18n/stackblitz.json

@@ -0,0 +1,12 @@
+{
+    "description": "i18n",
+    "files":[
+      "!**/*.d.ts",
+      "!**/*.js",
+      "!**/*.[0-9].*",
+      "!doc-files/**/*",	
+      "**/*.xlf"
+    ],
+    "file": "src/app/app.component.ts", 
+    "tags": ["Angular", "i18n", "internationalization"]
+}

aio/content/examples/i18n/zipper.json

@@ -1,9 +0,0 @@
-{
-  "files": [
-    "!dist/",
-    "!**/*.d.ts",
-    "!src/**/*.js",
-    "!doc-files/**/*",
-    "**/*.xlf"
-  ]
-}

aio/content/examples/pipes/src/app/app.component.ts

@@ -6,5 +6,5 @@ import { Component } from '@angular/core';
   templateUrl: './app.component.html'
 })
 export class AppComponent {
-  birthday = new Date(1988, 3, 15); // April 15, 1988
+  birthday = new Date(1988, 3, 15); // April 15, 1988 -- since month parameter is zero-based
 }

aio/content/examples/pipes/src/app/hero-birthday1.component.ts

@@ -8,5 +8,5 @@ import { Component } from '@angular/core';
   // #enddocregion hero-birthday-template
 })
 export class HeroBirthdayComponent {
-  birthday = new Date(1988, 3, 15); // April 15, 1988
+  birthday = new Date(1988, 3, 15); // April 15, 1988 -- since month parameter is zero-based
 }

aio/content/examples/pipes/src/app/hero-birthday2.component.ts

@@ -12,7 +12,7 @@ import { Component } from '@angular/core';
 })
 // #docregion class
 export class HeroBirthday2Component {
-  birthday = new Date(1988, 3, 15); // April 15, 1988
+  birthday = new Date(1988, 3, 15); // April 15, 1988 -- since month parameter is zero-based
   toggle = true; // start with true == shortDate
 
   get format()   { return this.toggle ? 'shortDate' : 'fullDate'; }

aio/content/examples/providers/src/app/user.service.2.ts

@@ -0,0 +1,7 @@
+import { Injectable } from '@angular/core';
+
+@Injectable({
+  providedIn: 'any',
+})
+export class UserService {
+}

aio/content/examples/router/src/app/app-routing.module.8.ts

@@ -6,13 +6,11 @@ import { Routes, RouterModule } from '@angular/router'; // CLI imports router
 const routes: Routes = [
   { path: 'first-component', component: FirstComponent },
   { path: 'second-component', component: SecondComponent },
-  // #enddocregion routes
+  // #enddocregion routes, routes-with-wildcard
   { path: '',   redirectTo: '/first-component', pathMatch: 'full' }, // redirect to `first-component`
-  { path: '**', component: FirstComponent },
-  // #enddocregion redirect
+  // #docregion routes-with-wildcard
   { path: '**', component: PageNotFoundComponent },  // Wildcard route for a 404 page
   // #docregion routes
-  // #docregion redirect
 ];
 // #enddocregion routes, routes-with-wildcard, redirect
 

aio/content/examples/schematics-for-libraries/projects/my-lib/package.json

@@ -16,5 +16,12 @@
     "@angular/core": "^7.2.0"
   },
 // #docregion collection
-  "schematics": "./schematics/collection.json"
-}
+  "schematics": "./schematics/collection.json",
+// #enddocregion collection
+// #docregion ng-add
+  "ng-add": {
+    "save": "devDependencies"
+  }
+// #enddocregion ng-add
+// #docregion collection
+}

aio/content/examples/toh-pt4/src/app/heroes/heroes.component.ts

@@ -33,7 +33,7 @@ export class HeroesComponent implements OnInit {
 
   onSelect(hero: Hero): void {
     this.selectedHero = hero;
-    this.messageService.add(`HeroService: Selected hero id=${hero.id}`);
+    this.messageService.add(`HeroesComponent: Selected hero id=${hero.id}`);
   }
 
   // #docregion getHeroes

aio/content/guide/accessibility.md

@@ -20,7 +20,7 @@ work well for all users, including those who rely on assistive technologies.
 
 Building accessible web experience often involves setting [ARIA attributes](https://developers.google.com/web/fundamentals/accessibility/semantics-aria)
 to provide semantic meaning where it might otherwise be missing.
-Use [attribute binding](guide/template-syntax#attribute-binding) template syntax to control the values of accessibility-related attributes.
+Use [attribute binding](guide/attribute-binding) template syntax to control the values of accessibility-related attributes.
 
 When binding to ARIA attributes in Angular, you must use the `attr.` prefix, as the ARIA
 specification depends specifically on HTML attributes rather than properties of DOM elements.
@@ -44,7 +44,7 @@ NOTE:
 
    By convention, HTML attributes use lowercase names (`tabindex`), while properties use camelCase names (`tabIndex`).
 
-   See the [Template Syntax](guide/template-syntax#html-attribute-vs-dom-property) guide for more background on the difference between attributes and properties.
+   See the [Binding syntax](guide/binding-syntax#html-attribute-vs-dom-property) guide for more background on the difference between attributes and properties.
 
 </div>
 

aio/content/guide/ajs-quick-reference.md

@@ -74,8 +74,7 @@ The following table lists some of the key AngularJS template features with their
       The context of the binding is implied and is always the
       associated component, so it needs no reference variable.
 
-      For more information, see the [Interpolation](guide/template-syntax#interpolation)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information, see the [Interpolation](guide/interpolation) guide.
     </td>
 
   </tr>
@@ -141,8 +140,8 @@ The following table lists some of the key AngularJS template features with their
 
       Angular has true template input variables that are explicitly defined using the `let` keyword.
 
-      For more information, see the [ngFor micro-syntax](guide/template-syntax#microsyntax)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information, see the [ngFor micro-syntax](guide/built-in-directives#microsyntax)
+      section of the [Built-in Directives](guide/built-in-directives) page.
     </td>
 
   </tr>
@@ -258,8 +257,7 @@ The following are some of the key AngularJS built-in directives and their equiva
       Angular also has **class binding**, which is a good way to add or remove a single class,
       as shown in the third example.
 
-      For more information see the [Attribute, class, and style bindings](guide/template-syntax#other-bindings)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information see [Attribute, class, and style bindings](guide/attribute-binding) page.
 
     </td>
 
@@ -309,8 +307,7 @@ The following are some of the key AngularJS built-in directives and their equiva
 
       For a list of DOM events, see: https://developer.mozilla.org/en-US/docs/Web/Events.
 
-      For more information, see the [Event binding](guide/template-syntax#event-binding)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information, see the [Event binding](guide/event-binding) page.
 
     </td>
 
@@ -407,8 +404,7 @@ The following are some of the key AngularJS built-in directives and their equiva
       Angular uses property binding; there is no built-in *href* directive.
       Place the element's `href` property in square brackets and set it to a quoted template expression.
 
-      For more information see the [Property binding](guide/template-syntax#property-binding)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information see the [Property binding](guide/property-binding) page.
 
       In Angular, `href` is no longer used for routing. Routing uses `routerLink`, as shown in the following example.
 
@@ -487,8 +483,8 @@ The following are some of the key AngularJS built-in directives and their equiva
       and event binding (from the view to the component), thereby providing two-way binding.
 
       For more information on two-way binding with `ngModel`, see the [NgModel&mdash;Two-way binding to
-      form elements with `[(ngModel)]`](../guide/template-syntax.html#ngModel)
-      section of the [Template Syntax](guide/template-syntax) page.
+      form elements with `[(ngModel)]`](../guide/built-in-directives#ngModel)
+      section of the [Built-in directives](guide/built-in-directives) page.
     </td>
 
   </tr>
@@ -570,8 +566,7 @@ The following are some of the key AngularJS built-in directives and their equiva
 
       In this example, the `<div>` element is hidden if the `favoriteHero` variable is not truthy.
 
-      For more information on property binding, see the [Property binding](guide/template-syntax#property-binding)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information on property binding, see the [Property binding](guide/property-binding) page.
     </td>
 
   </tr>
@@ -604,8 +599,7 @@ The following are some of the key AngularJS built-in directives and their equiva
       Angular uses property binding; there is no built-in *src* directive.
       Place the `src` property in square brackets and set it to a quoted template expression.
 
-      For more information on property binding, see the [Property binding](guide/template-syntax#property-binding)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information on property binding, see the [Property binding](guide/property-binding) page.
     </td>
 
   </tr>
@@ -644,11 +638,11 @@ The following are some of the key AngularJS built-in directives and their equiva
 
       Angular also has **style binding**, which is good way to set a single style. This is shown in the second example.
 
-      For more information on style binding, see the [Style binding](guide/template-syntax#style-binding) section of the
-      [Template Syntax](guide/template-syntax) page.
+      For more information on style binding, see the [Style binding](guide/attribute-binding#style-binding) section of the
+      [Attribute binding](guide/attribute-binding) page.
 
-      For more information on the `ngStyle` directive, see [NgStyle](guide/template-syntax#ngStyle)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information on the `ngStyle` directive, see the [NgStyle](guide/built-in-directives#ngStyle)
+      section of the [Built-in directives](guide/built-in-directives) page.
     </td>
 
   </tr>
@@ -704,8 +698,8 @@ The following are some of the key AngularJS built-in directives and their equiva
 
       The (*) before `ngSwitchCase` and `ngSwitchDefault` is required in this example.
 
-      For more information, see [The NgSwitch directives](guide/template-syntax#ngSwitch)
-      section of the [Template Syntax](guide/template-syntax) page.
+      For more information, see [The NgSwitch directives](guide/built-in-directives#ngSwitch)
+      section of the [Built-in directives](guide/built-in-directives) page.
     </td>
 
   </tr>

aio/content/guide/angular-compiler-options.md

@@ -1,6 +1,6 @@
 # Angular compiler options
 
-When you use [AOT compilation](guide/aot-compiler), you can control how your application is compiled by specifying *template* compiler options in the `tsconfig.json` [TypeScript configuration file](guide/typescript-configuration).
+When you use [AOT compilation](guide/aot-compiler), you can control how your application is compiled by specifying *template* compiler options in the [TypeScript configuration file](guide/typescript-configuration).
 
 The template options object, `angularCompilerOptions`, is a sibling to the `compilerOptions` object that supplies standard options to the TypeScript compiler.
 
@@ -21,11 +21,11 @@ The template options object, `angularCompilerOptions`, is a sibling to the `comp
 {@a tsconfig-extends}
 ## Configuration inheritance with extends
 
-Like the TypeScript compiler, The Angular AOT compiler also supports `extends` in the `angularCompilerOptions` section of the TypeScript configuration file, `tsconfig.json`.
+Like the TypeScript compiler, The Angular AOT compiler also supports `extends` in the `angularCompilerOptions` section of the TypeScript configuration file.
 The `extends` property is at the top level, parallel to `compilerOptions` and `angularCompilerOptions`.
 
 A TypeScript configuration can inherit settings from another file using the `extends` property.
-The configuration options from the base file are loaded first, then overridden by those in the inheriting `tsconfig` file.
+The configuration options from the base file are loaded first, then overridden by those in the inheriting configuration file.
 
 For example:
 
@@ -186,7 +186,7 @@ For library projects generated with the CLI, the dev configuration default is `t
 
 When `true` (recommended), reports an error for a supplied parameter whose injection type cannot be determined. When `false` (currently the default), constructor parameters of classes marked with `@Injectable` whose type cannot be resolved produce a warning.
 
-When you use the CLI command `ng new`, it is set to `true` by default in the generated project's configuration.
+When you use the CLI command `ng new --strict`, it is set to `true` in the generated project's configuration.
 
 ### `strictTemplates`
 
@@ -194,6 +194,7 @@ When `true`, enables [strict template type checking](guide/template-typecheck#st
 
 Additional strictness flags allow you to enable and disable specific types of strict template type checking. See [troubleshooting template errors](guide/template-typecheck#troubleshooting-template-errors).
 
+When you use the CLI command `ng new --strict`, it is set to `true` in the generated project's configuration.
 
 ### `trace`
 

aio/content/guide/aot-compiler.md

@@ -105,7 +105,7 @@ For help in understanding and resolving these problems, see [AOT Metadata Errors
 
 ### Configuring AOT compilation
 
-You can provide options in the `tsconfig.json` [TypeScript configuration file](guide/typescript-configuration) that control the compilation process. See [Angular compiler options](guide/angular-compiler-options) for a complete list of available options.
+You can provide options in the [TypeScript configuration file](guide/typescript-configuration) that controls the compilation process. See [Angular compiler options](guide/angular-compiler-options) for a complete list of available options.
 
 ## Phase 1: Code analysis
 
@@ -211,7 +211,7 @@ The compiler later reports the error if it needs that piece of metadata to gener
 
 <div class="alert is-helpful">
 
- If you want `ngc` to report syntax errors immediately rather than produce a `.metadata.json` file with errors, set the `strictMetadataEmit` option in the TypeScript configuration file, `tsconfig.json`.
+ If you want `ngc` to report syntax errors immediately rather than produce a `.metadata.json` file with errors, set the `strictMetadataEmit` option in the TypeScript configuration file.
 
 ```
   "angularCompilerOptions": {
@@ -548,7 +548,7 @@ It does not, however, rewrite the `.d.ts` file, so TypeScript doesn't recognize
 One of the Angular compiler's most helpful features is the ability to type-check expressions within templates, and catch any errors before they cause crashes at runtime.
 In the template type-checking phase, the Angular template compiler uses the TypeScript compiler to validate the binding expressions in templates.
 
-Enable this phase explicitly by adding the compiler option `"fullTemplateTypeCheck"` in the `"angularCompilerOptions"` of the project's `tsconfig.json`
+Enable this phase explicitly by adding the compiler option `"fullTemplateTypeCheck"` in the `"angularCompilerOptions"` of the project's TypeScript configuration file
 (see [Angular Compiler Options](guide/angular-compiler-options)).
 
 <div class="alert is-helpful">
@@ -623,7 +623,7 @@ For more information about input type narrowing, see [Input setter coercion](gui
 
 ### Non-null type assertion operator
 
-Use the [non-null type assertion operator](guide/template-syntax#non-null-assertion-operator) to suppress the `Object is possibly 'undefined'` error when it is inconvenient to use `*ngIf` or when some constraint in the component ensures that the expression is always non-null when the binding expression is interpolated.
+Use the [non-null type assertion operator](guide/template-expression-operators#non-null-assertion-operator) to suppress the `Object is possibly 'undefined'` error when it is inconvenient to use `*ngIf` or when some constraint in the component ensures that the expression is always non-null when the binding expression is interpolated.
 
 In the following example, the `person` and `address` properties are always set together, implying that `address` is always non-null if `person` is non-null.
 There is no convenient way to describe this constraint to TypeScript and the template compiler, but the error is suppressed in the example by using `address!.street`.

aio/content/guide/aot-metadata-errors.md

@@ -430,7 +430,7 @@ Angular does something similar with the `DOCUMENT` token so you can inject the b
 
 ```ts
 import { Inject }   from '@angular/core';
-import { DOCUMENT } from '@angular/platform-browser';
+import { DOCUMENT } from '@angular/common';
 
 @Component({ ... })
 export class MyComponent {

aio/content/guide/architecture-components.md

@@ -92,7 +92,7 @@ This example from the `HeroListComponent` template uses three of these forms.
 * The `{{hero.name}}` [*interpolation*](guide/displaying-data#interpolation)
 displays the component's `hero.name` property value within the `<li>` element.
 
-* The `[hero]` [*property binding*](guide/template-syntax#property-binding) passes the value of
+* The `[hero]` [*property binding*](guide/property-binding) passes the value of
 `selectedHero` from the parent `HeroListComponent` to the `hero` property of the child `HeroDetailComponent`.
 
 * The `(click)` [*event binding*](guide/user-input#binding-to-user-input-events) calls the component's `selectHero` method when the user clicks a hero's name.
@@ -126,7 +126,7 @@ Angular pipes let you declare display-value transformations in your template HTM
 
 Angular defines various pipes, such as the [date](https://angular.io/api/common/DatePipe) pipe and [currency](https://angular.io/api/common/CurrencyPipe) pipe; for a complete list, see the [Pipes API list](https://angular.io/api?type=pipe). You can also define new pipes.
 
-To specify a value transformation in an HTML template, use the [pipe operator (|)](https://angular.io/guide/template-syntax#pipe).
+To specify a value transformation in an HTML template, use the [pipe operator (|)](https://angular.io/guide/template-expression-operators#pipe).
 
 `{{interpolated_value | pipe_name}}`
 
@@ -179,9 +179,9 @@ The `ngModel` directive, which implements two-way data binding, is an example of
 <code-example path="architecture/src/app/hero-detail.component.html" header="src/app/hero-detail.component.html (ngModel)" region="ngModel"></code-example>
 
 Angular has more pre-defined directives that either alter the layout structure
-(for example, [ngSwitch](guide/template-syntax#ngSwitch))
+(for example, [ngSwitch](guide/built-in-directives#ngSwitch))
 or modify aspects of DOM elements and components
-(for example, [ngStyle](guide/template-syntax#ngStyle) and [ngClass](guide/template-syntax#ngClass)).
+(for example, [ngStyle](guide/built-in-directives#ngStyle) and [ngClass](guide/built-in-directives#ngClass)).
 
 <div class="alert is-helpful">
 

aio/content/guide/architecture.md

@@ -11,7 +11,7 @@ The basic building blocks are *NgModules*, which provide a compilation context f
 
 * Components use *services*, which provide specific functionality not directly related to views. Service providers can be *injected* into components as *dependencies*, making your code modular, reusable, and efficient.
 
-Both components and services are simply classes, with *decorators* that mark their type and provide metadata that tells Angular how to use them.
+Modules, components and services are classes that use *decorators*. These decorators mark their type and provide metadata that tells Angular how to use them.
 
 * The metadata for a component class associates it with a *template* that defines a view. A template combines ordinary HTML with Angular *directives* and *binding markup* that allow Angular to modify the HTML before rendering it for display.
 

aio/content/guide/attribute-binding.md

@@ -0,0 +1,303 @@
+# Attribute, class, and style bindings
+
+The template syntax provides specialized one-way bindings for scenarios less well-suited to property binding.
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+
+## Attribute binding
+
+Set the value of an attribute directly with an **attribute binding**. This is the only exception to the rule that a binding sets a target property and the only binding that creates and sets an attribute.
+
+Usually, setting an element property with a [property binding](guide/property-binding)
+is preferable to setting the attribute with a string. However, sometimes
+there is no element property to bind, so attribute binding is the solution.
+
+Consider the [ARIA](https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA) and
+[SVG](https://developer.mozilla.org/en-US/docs/Web/SVG). They are purely attributes, don't correspond to element properties, and don't set element properties. In these cases, there are no property targets to bind to.
+
+Attribute binding syntax resembles property binding, but
+instead of an element property between brackets, start with the prefix `attr`,
+followed by a dot (`.`), and the name of the attribute.
+You then set the attribute value, using an expression that resolves to a string,
+or remove the attribute when the expression resolves to `null`.
+
+One of the primary use cases for attribute binding
+is to set ARIA attributes, as in this example:
+
+<code-example path="attribute-binding/src/app/app.component.html" region="attrib-binding-aria" header="src/app/app.component.html"></code-example>
+
+{@a colspan}
+
+<div class="alert is-helpful">
+
+#### `colspan` and `colSpan`
+
+Notice the difference between the `colspan` attribute and the `colSpan` property.
+
+If you wrote something like this:
+
+<code-example language="html">
+  &lt;tr&gt;&lt;td colspan="{{1 + 1}}"&gt;Three-Four&lt;/td&gt;&lt;/tr&gt;
+</code-example>
+
+You'd get this error:
+
+<code-example language="bash">
+  Template parse errors:
+  Can't bind to 'colspan' since it isn't a known native property
+</code-example>
+
+As the message says, the `<td>` element does not have a `colspan` property. This is true
+because `colspan` is an attribute&mdash;`colSpan`, with a capital `S`, is the
+corresponding property. Interpolation and property binding can set only *properties*, not attributes.
+
+Instead, you'd use property binding and write it like this:
+
+<code-example path="attribute-binding/src/app/app.component.html" region="colSpan" header="src/app/app.component.html"></code-example>
+
+</div>
+
+<hr/>
+
+{@a class-binding}
+
+## Class binding
+
+Here's how to set the `class` attribute without a binding in plain HTML:
+
+```html
+<!-- standard class attribute setting -->
+<div class="foo bar">Some text</div>
+```
+
+You can also add and remove CSS class names from an element's `class` attribute with a **class binding**.
+
+To create a single class binding, start with the prefix `class` followed by a dot (`.`) and the name of the CSS class (for example, `[class.foo]="hasFoo"`).
+Angular adds the class when the bound expression is truthy, and it removes the class when the expression is falsy (with the exception of `undefined`, see [styling delegation](#styling-delegation)).
+
+To create a binding to multiple classes, use a generic `[class]` binding without the dot (for example, `[class]="classExpr"`).
+The expression can be a space-delimited string of class names, or you can format it as an object with class names as the keys and truthy/falsy expressions as the values.
+With object format, Angular will add a class only if its associated value is truthy.
+
+It's important to note that with any object-like expression (`object`, `Array`, `Map`, `Set`, etc), the identity of the object must change for the class list to be updated.
+Updating the property without changing object identity will have no effect.
+
+If there are multiple bindings to the same class name, conflicts are resolved using [styling precedence](#styling-precedence).
+
+<style>
+  td, th {vertical-align: top}
+</style>
+
+<table width="100%">
+  <col width="15%">
+  </col>
+  <col width="20%">
+  </col>
+  <col width="35%">
+  </col>
+  <col width="30%">
+  </col>
+  <tr>
+    <th>
+      Binding Type
+    </th>
+    <th>
+      Syntax
+    </th>
+    <th>
+      Input Type
+    </th>
+    <th>
+      Example Input Values
+    </th>
+  </tr>
+  <tr>
+    <td>Single class binding</td>
+    <td><code>[class.foo]="hasFoo"</code></td>
+    <td><code>boolean | undefined | null</code></td>
+    <td><code>true</code>, <code>false</code></td>
+  </tr>
+  <tr>
+    <td rowspan=3>Multi-class binding</td>
+    <td rowspan=3><code>[class]="classExpr"</code></td>
+    <td><code>string</code></td>
+    <td><code>"my-class-1 my-class-2 my-class-3"</code></td>
+  </tr>
+  <tr>
+    <td><code>{[key: string]: boolean | undefined | null}</code></td>
+    <td><code>{foo: true, bar: false}</code></td>
+  </tr>
+  <tr>
+    <td><code>Array</code><<code>string</code>></td>
+    <td><code>['foo', 'bar']</code></td>
+  </tr>
+</table>
+
+
+The [NgClass](guide/built-in-directives/#ngclass) directive can be used as an alternative to direct `[class]` bindings.
+However, using the above class binding syntax without `NgClass` is preferred because due to improvements in class binding in Angular, `NgClass` no longer provides significant value, and might eventually be removed in the future.
+
+
+<hr/>
+
+## Style binding
+
+Here's how to set the `style` attribute without a binding in plain HTML:
+
+```html
+<!-- standard style attribute setting -->
+<div style="color: blue">Some text</div>
+```
+
+You can also set styles dynamically with a **style binding**.
+
+To create a single style binding, start with the prefix `style` followed by a dot (`.`) and the name of the CSS style property (for example, `[style.width]="width"`).
+The property will be set to the value of the bound expression, which is normally a string.
+Optionally, you can add a unit extension like `em` or `%`, which requires a number type.
+
+<div class="alert is-helpful">
+
+Note that a _style property_ name can be written in either
+[dash-case](guide/glossary#dash-case), as shown above, or
+[camelCase](guide/glossary#camelcase), such as `fontSize`.
+
+</div>
+
+If there are multiple styles you'd like to toggle, you can bind to the `[style]` property directly without the dot (for example, `[style]="styleExpr"`).
+The expression attached to the `[style]` binding is most often a string list of styles like `"width: 100px; height: 100px;"`.
+
+You can also format the expression as an object with style names as the keys and style values as the values, like `{width: '100px', height: '100px'}`.
+It's important to note that with any object-like expression (`object`, `Array`, `Map`, `Set`, etc), the identity of the object must change for the class list to be updated.
+Updating the property without changing object identity will have no effect.
+
+If there are multiple bindings to the same style property, conflicts are resolved using [styling precedence rules](#styling-precedence).
+
+<style>
+  td, th {vertical-align: top}
+</style>
+
+<table width="100%">
+  <col width="15%">
+  </col>
+  <col width="20%">
+  </col>
+  <col width="35%">
+  </col>
+  <col width="30%">
+  </col>
+  <tr>
+    <th>
+      Binding Type
+    </th>
+    <th>
+      Syntax
+    </th>
+    <th>
+      Input Type
+    </th>
+    <th>
+      Example Input Values
+    </th>
+  </tr>
+  <tr>
+    <td>Single style binding</td>
+    <td><code>[style.width]="width"</code></td>
+    <td><code>string | undefined | null</code></td>
+    <td><code>"100px"</code></td>
+  </tr>
+  <tr>
+  <tr>
+    <td>Single style binding with units</td>
+    <td><code>[style.width.px]="width"</code></td>
+    <td><code>number | undefined | null</code></td>
+    <td><code>100</code></td>
+  </tr>
+    <tr>
+    <td rowspan=3>Multi-style binding</td>
+    <td rowspan=3><code>[style]="styleExpr"</code></td>
+    <td><code>string</code></td>
+    <td><code>"width: 100px; height: 100px"</code></td>
+  </tr>
+  <tr>
+    <td><code>{[key: string]: string | undefined | null}</code></td>
+    <td><code>{width: '100px', height: '100px'}</code></td>
+  </tr>
+  <tr>
+    <td><code>Array</code><<code>string</code>></td>
+    <td><code>['width', '100px']</code></td>
+  </tr>
+</table>
+
+The [NgStyle](guide/built-in-directives/#ngstyle) directive can be used as an alternative to direct `[style]` bindings.
+However, using the above style binding syntax without `NgStyle` is preferred because due to improvements in style binding in Angular, `NgStyle` no longer provides significant value, and might eventually be removed in the future.
+
+
+<hr/>
+
+{@a styling-precedence}
+
+## Styling Precedence
+
+A single HTML element can have its CSS class list and style values bound to multiple sources (for example, host bindings from multiple directives).
+
+When there are multiple bindings to the same class name or style property, Angular uses a set of precedence rules to resolve conflicts and determine which classes or styles are ultimately applied to the element.
+
+<div class="alert is-helpful">
+<h4>Styling precedence (highest to lowest)</h4>
+
+1. Template bindings
+    1. Property binding (for example, `<div [class.foo]="hasFoo">` or `<div [style.color]="color">`)
+    1. Map binding (for example, `<div [class]="classExpr">` or `<div [style]="styleExpr">`)
+    1. Static value (for example, `<div class="foo">` or `<div style="color: blue">`)
+1. Directive host bindings
+    1. Property binding (for example, `host: {'[class.foo]': 'hasFoo'}` or `host: {'[style.color]': 'color'}`)
+    1. Map binding (for example, `host: {'[class]': 'classExpr'}` or `host: {'[style]': 'styleExpr'}`)
+    1. Static value (for example, `host: {'class': 'foo'}` or `host: {'style': 'color: blue'}`)
+1. Component host bindings
+    1. Property binding (for example, `host: {'[class.foo]': 'hasFoo'}` or `host: {'[style.color]': 'color'}`)
+    1. Map binding (for example, `host: {'[class]': 'classExpr'}` or `host: {'[style]': 'styleExpr'}`)
+    1. Static value (for example, `host: {'class': 'foo'}` or `host: {'style': 'color: blue'}`)
+
+</div>
+
+The more specific a class or style binding is, the higher its precedence.
+
+A binding to a specific class (for example, `[class.foo]`) will take precedence over a generic `[class]` binding, and a binding to a specific style (for example, `[style.bar]`) will take precedence over a generic `[style]` binding.
+
+<code-example path="attribute-binding/src/app/app.component.html" region="basic-specificity" header="src/app/app.component.html"></code-example>
+
+Specificity rules also apply when it comes to bindings that originate from different sources.
+It's possible for an element to have bindings in the template where it's declared, from host bindings on matched directives, and from host bindings on matched components.
+
+Template bindings are the most specific because they apply to the element directly and exclusively, so they have the highest precedence.
+
+Directive host bindings are considered less specific because directives can be used in multiple locations, so they have a lower precedence than template bindings.
+
+Directives often augment component behavior, so host bindings from components have the lowest precedence.
+
+<code-example path="attribute-binding/src/app/app.component.html" region="source-specificity" header="src/app/app.component.html"></code-example>
+
+In addition, bindings take precedence over static attributes.
+
+In the following case, `class` and `[class]` have similar specificity, but the `[class]` binding will take precedence because it is dynamic.
+
+<code-example path="attribute-binding/src/app/app.component.html" region="dynamic-priority" header="src/app/app.component.html"></code-example>
+
+{@a styling-delegation}
+### Delegating to styles with lower precedence
+
+It is possible for higher precedence styles to "delegate" to lower precedence styles using `undefined` values.
+Whereas setting a style property to `null` ensures the style is removed, setting it to `undefined` will cause Angular to fall back to the next-highest precedence binding to that style.
+
+For example, consider the following template:
+
+<code-example path="attribute-binding/src/app/app.component.html" region="style-delegation" header="src/app/app.component.html"></code-example>
+
+Imagine that the `dirWithHostBinding` directive and the `comp-with-host-binding` component both have a `[style.width]` host binding.
+In that case, if `dirWithHostBinding` sets its binding to `undefined`, the `width` property will fall back to the value of the `comp-with-host-binding` host binding.
+However, if `dirWithHostBinding` sets its binding to `null`, the `width` property will be removed entirely.

aio/content/guide/attribute-directives.md

@@ -18,12 +18,12 @@ There are three kinds of directives in Angular:
 You saw a component for the first time in the [Getting Started](start "Getting Started with Angular") tutorial.
 
 *Structural Directives* change the structure of the view.
-Two examples are [NgFor](guide/template-syntax#ngFor) and [NgIf](guide/template-syntax#ngIf).
+Two examples are [NgFor](guide/built-in-directives#ngFor) and [NgIf](guide/built-in-directives#ngIf).
 Learn about them in the [Structural Directives](guide/structural-directives) guide.
 
 *Attribute directives* are used as attributes of elements.
-The built-in [NgStyle](guide/template-syntax#ngStyle) directive in the
-[Template Syntax](guide/template-syntax) guide, for example,
+The built-in [NgStyle](guide/built-in-directives#ngStyle) directive in the
+[Built-in directives](guide/built-in-directives) guide, for example,
 can change several element styles at the same time.
 
 ## Build a simple attribute directive

aio/content/guide/binding-syntax.md

@@ -0,0 +1,318 @@
+
+# Binding syntax: an overview
+
+Data-binding is a mechanism for coordinating what users see, specifically
+with application data values.
+While you could push values to and pull values from HTML,
+the application is easier to write, read, and maintain if you turn these tasks over to a binding framework.
+You simply declare bindings between binding sources, target HTML elements, and let the framework do the rest.
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+Angular provides many kinds of data-binding. Binding types can be grouped into three categories distinguished by the direction of data flow:
+
+* From the _source-to-view_
+* From _view-to-source_
+* Two-way sequence: _view-to-source-to-view_
+
+<style>
+  td, th {vertical-align: top}
+</style>
+
+<table width="100%">
+  <col width="30%">
+  </col>
+  <col width="50%">
+  </col>
+  <col width="20%">
+  </col>
+  <tr>
+    <th>
+      Type
+    </th>
+    <th>
+      Syntax
+    </th>
+    <th>
+      Category
+    </th>
+
+  </tr>
+  <tr>
+     <td>
+      Interpolation<br>
+      Property<br>
+      Attribute<br>
+      Class<br>
+      Style
+    </td>
+    <td>
+
+      <code-example>
+        {{expression}}
+        [target]="expression"
+        bind-target="expression"
+      </code-example>
+
+    </td>
+
+    <td>
+      One-way<br>from data source<br>to view target
+    </td>
+    <tr>
+      <td>
+        Event
+      </td>
+      <td>
+        <code-example>
+          (target)="statement"
+          on-target="statement"
+        </code-example>
+      </td>
+
+      <td>
+        One-way<br>from view target<br>to data source
+      </td>
+    </tr>
+    <tr>
+      <td>
+        Two-way
+      </td>
+      <td>
+        <code-example>
+          [(target)]="expression"
+          bindon-target="expression"
+        </code-example>
+      </td>
+      <td>
+        Two-way
+      </td>
+    </tr>
+  </tr>
+</table>
+
+Binding types other than interpolation have a **target name** to the left of the equal sign, either surrounded by punctuation, `[]` or `()`,
+or preceded by a prefix: `bind-`, `on-`, `bindon-`.
+
+The *target* of a binding is the property or event inside the binding punctuation: `[]`, `()` or `[()]`.
+
+Every public member of a **source** directive is automatically available for binding.
+You don't have to do anything special to access a directive member in a template expression or statement.
+
+
+### Data-binding and HTML
+
+In the normal course of HTML development, you create a visual structure with HTML elements, and
+you modify those elements by setting element attributes with string constants.
+
+```html
+<div class="special">Plain old HTML</div>
+<img src="images/item.png">
+<button disabled>Save</button>
+```
+
+With data-binding, you can control things like the state of a button:
+
+<code-example path="binding-syntax/src/app/app.component.html" region="disabled-button" header="src/app/app.component.html"></code-example>
+
+Notice that the binding is to the `disabled` property of the button's DOM element,
+**not** the attribute. This applies to data-binding in general. Data-binding works with *properties* of DOM elements, components, and directives, not HTML *attributes*.
+
+{@a html-attribute-vs-dom-property}
+
+### HTML attribute vs. DOM property
+
+The distinction between an HTML attribute and a DOM property is key to understanding
+how Angular binding works. **Attributes are defined by HTML. Properties are accessed from DOM (Document Object Model) nodes.**
+
+* A few HTML attributes have 1:1 mapping to properties; for example, `id`.
+
+* Some HTML attributes don't have corresponding properties; for example, `aria-*`.
+
+* Some DOM properties don't have corresponding attributes; for example, `textContent`.
+
+It is important to remember that *HTML attribute* and the *DOM property* are different things, even when they have the same name.
+In Angular, the only role of HTML attributes is to initialize element and directive state.
+
+**Template binding works with *properties* and *events*, not *attributes*.**
+
+When you write a data-binding, you're dealing exclusively with the *DOM properties* and *events* of the target object.
+
+<div class="alert is-helpful">
+
+This general rule can help you build a mental model of attributes and DOM properties:
+**Attributes initialize DOM properties and then they are done.
+Property values can change; attribute values can't.**
+
+There is one exception to this rule.
+Attributes can be changed by `setAttribute()`, which re-initializes corresponding DOM properties.
+
+</div>
+
+For more information, see the [MDN Interfaces documentation](https://developer.mozilla.org/en-US/docs/Web/API#Interfaces) which has API docs for all the standard DOM elements and their properties.
+Comparing the [`<td>` attributes](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/td) attributes to the [`<td>` properties](https://developer.mozilla.org/en-US/docs/Web/API/HTMLTableCellElement) provides a helpful example for differentiation.
+In particular, you can navigate from the attributes page to the properties via "DOM interface" link, and navigate the inheritance hierarchy up to `HTMLTableCellElement`.
+
+
+#### Example 1: an `<input>`
+
+When the browser renders `<input type="text" value="Sarah">`, it creates a
+corresponding DOM node with a `value` property initialized to "Sarah".
+
+```html
+<input type="text" value="Sarah">
+```
+
+When the user enters "Sally" into the `<input>`, the DOM element `value` *property* becomes "Sally".
+However, if you look at the HTML attribute `value` using `input.getAttribute('value')`, you can see that the *attribute* remains unchanged&mdash;it returns "Sarah".
+
+The HTML attribute `value` specifies the *initial* value; the DOM `value` property is the *current* value.
+
+To see attributes versus DOM properties in a functioning app, see the <live-example name="binding-syntax"></live-example> especially for binding syntax.
+
+#### Example 2: a disabled button
+
+The `disabled` attribute is another example. A button's `disabled`
+*property* is `false` by default so the button is enabled.
+
+When you add the `disabled` *attribute*, its presence alone
+initializes the button's `disabled` *property* to `true`
+so the button is disabled.
+
+```html
+<button disabled>Test Button</button>
+```
+
+Adding and removing the `disabled` *attribute* disables and enables the button.
+However, the value of the *attribute* is irrelevant,
+which is why you cannot enable a button by writing `<button disabled="false">Still Disabled</button>`.
+
+To control the state of the button, set the `disabled` *property*,
+
+<div class="alert is-helpful">
+
+Though you could technically set the `[attr.disabled]` attribute binding, the values are different in that the property binding requires to a boolean value, while its corresponding attribute binding relies on whether the value is `null` or not. Consider the following:
+
+```html
+<input [disabled]="condition ? true : false">
+<input [attr.disabled]="condition ? 'disabled' : null">
+```
+
+Generally, use property binding over attribute binding as it is more intuitive (being a boolean value), has a shorter syntax, and is more performant.
+
+</div>
+
+
+To see the `disabled` button example in a functioning app, see the <live-example name="binding-syntax"></live-example> especially for binding syntax. This example shows you how to toggle the disabled property from the component.
+
+## Binding types and targets
+
+The **target of a data-binding** is something in the DOM.
+Depending on the binding type, the target can be a property (element, component, or directive),
+an event (element, component, or directive), or sometimes an attribute name.
+The following table summarizes the targets for the different binding types.
+
+<style>
+  td, th {vertical-align: top}
+</style>
+
+<table width="100%">
+  <col width="10%">
+  </col>
+  <col width="15%">
+  </col>
+  <col width="75%">
+  </col>
+  <tr>
+    <th>
+      Type
+    </th>
+    <th>
+      Target
+    </th>
+    <th>
+      Examples
+    </th>
+  </tr>
+  <tr>
+    <td>
+      Property
+    </td>
+    <td>
+      Element&nbsp;property<br>
+      Component&nbsp;property<br>
+      Directive&nbsp;property
+    </td>
+    <td>
+      <code>src</code>, <code>hero</code>, and <code>ngClass</code> in the following:
+      <code-example path="template-syntax/src/app/app.component.html" region="property-binding-syntax-1"></code-example>
+      <!-- For more information, see [Property Binding](guide/property-binding). -->
+    </td>
+  </tr>
+  <tr>
+    <td>
+      Event
+    </td>
+    <td>
+      Element&nbsp;event<br>
+      Component&nbsp;event<br>
+      Directive&nbsp;event
+    </td>
+    <td>
+      <code>click</code>, <code>deleteRequest</code>, and <code>myClick</code> in the following:
+      <code-example path="template-syntax/src/app/app.component.html" region="event-binding-syntax-1"></code-example>
+      <!-- KW--Why don't these links work in the table? -->
+      <!-- <div>For more information, see [Event Binding](guide/event-binding).</div> -->
+    </td>
+  </tr>
+  <tr>
+    <td>
+      Two-way
+    </td>
+    <td>
+      Event and property
+    </td>
+    <td>
+      <code-example path="template-syntax/src/app/app.component.html" region="2-way-binding-syntax-1"></code-example>
+    </td>
+  </tr>
+  <tr>
+    <td>
+      Attribute
+    </td>
+    <td>
+      Attribute
+      (the&nbsp;exception)
+    </td>
+    <td>
+      <code-example path="template-syntax/src/app/app.component.html" region="attribute-binding-syntax-1"></code-example>
+    </td>
+  </tr>
+  <tr>
+    <td>
+      Class
+    </td>
+    <td>
+      <code>class</code> property
+    </td>
+    <td>
+      <code-example path="template-syntax/src/app/app.component.html" region="class-binding-syntax-1"></code-example>
+    </td>
+  </tr>
+  <tr>
+    <td>
+      Style
+    </td>
+    <td>
+      <code>style</code> property
+    </td>
+    <td>
+      <code-example path="template-syntax/src/app/app.component.html" region="style-binding-syntax-1"></code-example>
+    </td>
+  </tr>
+</table>
+

aio/content/guide/build.md

@@ -262,6 +262,33 @@ Each budget entry is a JSON object with the following properties:
 
  </table>
 
+{@a commonjs }
+## Configuring CommonJS dependencies
+
+<div class="alert is-important">
+
+It is recommended that you avoid depending on CommonJS modules in your Angular applications.
+Depending on CommonJS modules can prevent bundlers and minifiers from optimizing your application, which results in larger bundle sizes.
+Instead, it is recommended that you use [ECMAScript modules](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import) in your entire application.
+For more information, see [How CommonJS is making your bundles larger](https://web.dev/commonjs-larger-bundles/).
+
+</div>
+
+The Angular CLI outputs warnings if it detects that your browser application depends on CommonJS modules.
+To disable these warnings, you can add the CommonJS module name to `allowedCommonJsDependencies` option in the `build` options located in `angular.json` file.
+
+<code-example lang="json">
+"build": {
+  "builder": "@angular-devkit/build-angular:browser",
+  "options": {
+     "allowedCommonJsDependencies": [
+        "lodash"
+     ]
+     ...
+   }
+   ...
+},
+</code-example>
 
 {@a browser-compat}
 

aio/content/guide/built-in-directives.md

@@ -0,0 +1,435 @@
+# Built-in directives
+
+Angular offers two kinds of built-in directives: [_attribute_ directives](guide/attribute-directives) and [_structural_ directives](guide/structural-directives).
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+For more detail, including how to build your own custom directives, see [Attribute Directives](guide/attribute-directives) and [Structural Directives](guide/structural-directives).
+
+<hr/>
+
+{@a attribute-directives}
+
+## Built-in attribute directives
+
+Attribute directives listen to and modify the behavior of
+other HTML elements, attributes, properties, and components.
+You usually apply them to elements as if they were HTML attributes, hence the name.
+
+Many NgModules such as the [`RouterModule`](guide/router "Routing and Navigation")
+and the [`FormsModule`](guide/forms "Forms") define their own attribute directives.
+The most common attribute directives are as follows:
+
+* [`NgClass`](guide/built-in-directives#ngClass)&mdash;adds and removes a set of CSS classes.
+* [`NgStyle`](guide/built-in-directives#ngStyle)&mdash;adds and removes a set of HTML styles.
+* [`NgModel`](guide/built-in-directives#ngModel)&mdash;adds two-way data binding to an HTML form element.
+
+<hr/>
+
+{@a ngClass}
+
+## `NgClass`
+
+Add or remove several CSS classes simultaneously with `ngClass`.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="special-div" header="src/app/app.component.html"></code-example>
+
+<div class="alert is-helpful">
+
+To add or remove a *single* class, use [class binding](guide/attribute-binding#class-binding) rather than `NgClass`.
+
+</div>
+
+Consider a `setCurrentClasses()` component method that sets a component property,
+`currentClasses`, with an object that adds or removes three classes based on the
+`true`/`false` state of three other component properties. Each key of the object is a CSS class name; its value is `true` if the class should be added,
+`false` if it should be removed.
+
+<code-example path="built-in-directives/src/app/app.component.ts" region="setClasses" header="src/app/app.component.ts"></code-example>
+
+Adding an `ngClass` property binding to `currentClasses` sets the element's classes accordingly:
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgClass-1" header="src/app/app.component.html"></code-example>
+
+<div class="alert is-helpful">
+
+Remember that in this situation you'd call `setCurrentClasses()`,
+both initially and when the dependent properties change.
+
+</div>
+
+<hr/>
+
+{@a ngStyle}
+
+## `NgStyle`
+
+Use `NgStyle` to set many inline styles simultaneously and dynamically, based on the state of the component.
+
+### Without `NgStyle`
+
+For context, consider setting a *single* style value with [style binding](guide/attribute-binding#style-binding), without `NgStyle`.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="without-ng-style" header="src/app/app.component.html"></code-example>
+
+However, to set *many* inline styles at the same time, use the `NgStyle` directive.
+
+The following is a `setCurrentStyles()` method that sets a component
+property, `currentStyles`, with an object that defines three styles,
+based on the state of three other component properties:
+
+<code-example path="built-in-directives/src/app/app.component.ts" region="setStyles" header="src/app/app.component.ts"></code-example>
+
+Adding an `ngStyle` property binding to `currentStyles` sets the element's styles accordingly:
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgStyle-2" header="src/app/app.component.html"></code-example>
+
+<div class="alert is-helpful">
+
+Remember to call `setCurrentStyles()`, both initially and when the dependent properties change.
+
+</div>
+
+
+<hr/>
+
+{@a ngModel}
+
+## `[(ngModel)]`: Two-way binding
+
+The `NgModel` directive allows you to display a data property and
+update that property when the user makes changes. Here's an example:
+
+<code-example path="built-in-directives/src/app/app.component.html" header="src/app/app.component.html (NgModel example)" region="NgModel-1"></code-example>
+
+
+### Import `FormsModule` to use `ngModel`
+
+Before using the `ngModel` directive in a two-way data binding,
+you must import the `FormsModule` and add it to the NgModule's `imports` list.
+Learn more about the `FormsModule` and `ngModel` in [Forms](guide/forms#ngModel).
+
+Remember to import the `FormsModule` to make `[(ngModel)]` available as follows:
+
+<code-example path="built-in-directives/src/app/app.module.ts" header="src/app/app.module.ts (FormsModule import)" region="import-forms-module"></code-example>
+
+
+You could achieve the same result with separate bindings to
+the `<input>` element's  `value` property and `input` event:
+
+<code-example path="built-in-directives/src/app/app.component.html" region="without-NgModel" header="src/app/app.component.html"></code-example>
+
+To streamline the syntax, the `ngModel` directive hides the details behind its own `ngModel` input and `ngModelChange` output properties:
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgModelChange" header="src/app/app.component.html"></code-example>
+
+The `ngModel` data property sets the element's value property and the `ngModelChange` event property
+listens for changes to the element's value.
+
+### `NgModel` and value accessors
+
+The details are specific to each kind of element and therefore the `NgModel` directive only works for an element
+supported by a [ControlValueAccessor](api/forms/ControlValueAccessor)
+that adapts an element to this protocol.
+Angular provides *value accessors* for all of the basic HTML form elements and the
+[Forms](guide/forms) guide shows how to bind to them.
+
+You can't apply `[(ngModel)]` to a non-form native element or a
+third-party custom component until you write a suitable value accessor. For more information, see
+the API documentation on [DefaultValueAccessor](https://angular.io/api/forms/DefaultValueAccessor).
+
+You don't need a value accessor for an Angular component that
+you write because you can name the value and event properties
+to suit Angular's basic [two-way binding syntax](guide/two-way-binding)
+and skip `NgModel` altogether.
+The `sizer` in the
+[Two-way Binding](guide/two-way-binding) section is an example of this technique.
+
+Separate `ngModel` bindings are an improvement over binding to the
+element's native properties, but you can streamline the binding with a
+single declaration using the `[(ngModel)]` syntax:
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgModel-1" header="src/app/app.component.html"></code-example>
+
+This `[(ngModel)]` syntax can only _set_ a data-bound property.
+If you need to do something more, you can write the expanded form;
+for example, the following changes the `<input>` value to uppercase:
+
+<code-example path="built-in-directives/src/app/app.component.html" region="uppercase" header="src/app/app.component.html"></code-example>
+
+Here are all variations in action, including the uppercase version:
+
+<div class="lightbox">
+  <img src='generated/images/guide/built-in-directives/ng-model-anim.gif' alt="NgModel variations">
+</div>
+
+<hr/>
+
+{@a structural-directives}
+
+## Built-in _structural_ directives
+
+Structural directives are responsible for HTML layout.
+They shape or reshape the DOM's structure, typically by adding, removing, and manipulating
+the host elements to which they are attached.
+
+This section is an introduction to the common built-in structural directives:
+
+* [`NgIf`](guide/built-in-directives#ngIf)&mdash;conditionally creates or destroys subviews from the template.
+* [`NgFor`](guide/built-in-directives#ngFor)&mdash;repeat a node for each item in a list.
+* [`NgSwitch`](guide/built-in-directives#ngSwitch)&mdash;a set of directives that switch among alternative views.
+
+<div class="alert is-helpful">
+
+The deep details of structural directives are covered in the
+[Structural Directives](guide/structural-directives) guide,
+which explains the following:
+
+* Why you
+[prefix the directive name with an asterisk (\*)](guide/structural-directives#the-asterisk--prefix).
+* Using [`<ng-container>`](guide/structural-directives#ngcontainer "<ng-container>")
+to group elements when there is no suitable host element for the directive.
+* How to write your own structural directive.
+* That you can only apply [one structural directive](guide/structural-directives#one-per-element "one per host element") to an element.
+
+</div>
+
+<hr/>
+
+{@a ngIf}
+
+## NgIf
+
+You can add or remove an element from the DOM by applying an `NgIf` directive to
+a host element.
+Bind the directive to a condition expression like `isActive` in this example.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgIf-1" header="src/app/app.component.html"></code-example>
+
+<div class="alert is-helpful">
+
+Don't forget the asterisk (`*`) in front of `ngIf`. For more information
+on the asterisk, see the [asterisk (*) prefix](guide/structural-directives#the-asterisk--prefix) section of
+[Structural Directives](guide/structural-directives).
+
+</div>
+
+When the `isActive` expression returns a truthy value, `NgIf` adds the
+`ItemDetailComponent` to the DOM.
+When the expression is falsy, `NgIf` removes the `ItemDetailComponent`
+from the DOM, destroying that component and all of its sub-components.
+
+
+### Show/hide vs. `NgIf`
+
+Hiding an element is different from removing it with `NgIf`.
+For comparison, the following example shows how to control
+the visibility of an element with a
+[class](guide/attribute-binding#class-binding) or [style](guide/attribute-binding#style-binding) binding.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgIf-3" header="src/app/app.component.html"></code-example>
+
+When you hide an element, that element and all of its descendants remain in the DOM.
+All components for those elements stay in memory and
+Angular may continue to check for changes.
+You could be holding onto considerable computing resources and degrading performance
+unnecessarily.
+
+`NgIf` works differently. When `NgIf` is `false`, Angular removes the element and its descendants from the DOM.
+It destroys their components, freeing up resources, which
+results in a better user experience.
+
+If you are hiding large component trees, consider `NgIf` as a more
+efficient alternative to showing/hiding.
+
+<div class="alert is-helpful">
+
+For more information on `NgIf` and `ngIfElse`, see the [API documentation about NgIf](api/common/NgIf).
+
+</div>
+
+### Guard against null
+
+Another advantage of `ngIf` is that you can use it to guard against null. Show/hide
+is best suited for very simple use cases, so when you need a guard, opt instead for `ngIf`. Angular will throw an error if a nested expression tries to access a property of `null`.
+
+The following shows `NgIf` guarding two `<div>`s.
+The `currentCustomer` name appears only when there is a `currentCustomer`.
+The `nullCustomer` will not be displayed as long as it is `null`.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgIf-2" header="src/app/app.component.html"></code-example>
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgIf-2b" header="src/app/app.component.html"></code-example>
+
+<div class="alert is-helpful">
+
+See also the
+[safe navigation operator](guide/template-expression-operators#safe-navigation-operator "Safe navigation operator (?.)") below.
+
+</div>
+<hr/>
+
+{@a ngFor}
+## `NgFor`
+
+`NgFor` is a repeater directive&mdash;a way to present a list of items.
+You define a block of HTML that defines how a single item should be displayed
+and then you tell Angular to use that block as a template for rendering each item in the list.
+The text assigned to `*ngFor` is the instruction that guides the repeater process.
+
+The following example shows `NgFor` applied to a simple `<div>`. (Don't forget the asterisk (`*`) in front of `ngFor`.)
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgFor-1" header="src/app/app.component.html"></code-example>
+
+<div class="alert is-helpful">
+
+Don't forget the asterisk (`*`) in front of `ngFor`. For more information
+on the asterisk, see the [asterisk (*) prefix](guide/structural-directives#the-asterisk--prefix) section of
+[Structural Directives](guide/structural-directives).
+
+</div>
+
+You can also apply an `NgFor` to a component element, as in the following example.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgFor-2" header="src/app/app.component.html"></code-example>
+
+{@a microsyntax}
+
+<div class="callout is-critical">
+<header>*ngFor microsyntax</header>
+
+The string assigned to `*ngFor` is not a [template expression](guide/interpolation). Rather,
+it's a *microsyntax*&mdash;a little language of its own that Angular interprets.
+The string `"let item of items"` means:
+
+> *Take each item in the `items` array, store it in the local `item` looping variable, and
+make it available to the templated HTML for each iteration.*
+
+Angular translates this instruction into an `<ng-template>` around the host element,
+then uses this template repeatedly to create a new set of elements and bindings for each `item`
+in the list.
+For more information about microsyntax, see the [Structural Directives](guide/structural-directives#microsyntax) guide.
+
+</div>
+
+
+{@a template-input-variable}
+
+{@a template-input-variables}
+
+### Template input variables
+
+The `let` keyword before `item` creates a template input variable called `item`.
+The `ngFor` directive iterates over the `items` array returned by the parent component's `items` property
+and sets `item` to the current item from the array during each iteration.
+
+Reference `item` within the `ngFor` host element
+as well as within its descendants to access the item's properties.
+The following example references `item` first in an interpolation
+and then passes in a binding to the `item` property of the `<app-item-detail>` component.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgFor-1-2" header="src/app/app.component.html"></code-example>
+
+For more information about template input variables, see
+[Structural Directives](guide/structural-directives#template-input-variable).
+
+### `*ngFor` with `index`
+
+The `index` property of the `NgFor` directive context
+returns the zero-based index of the item in each iteration.
+You can capture the `index` in a template input variable and use it in the template.
+
+The next example captures the `index` in a variable named `i` and displays it with the item name.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgFor-3" header="src/app/app.component.html"></code-example>
+
+<div class="alert is-helpful">
+
+`NgFor` is implemented by the `NgForOf` directive. Read more about the other `NgForOf` context values such as `last`, `even`,
+and `odd` in the [NgForOf API reference](api/common/NgForOf).
+
+</div>
+
+{@a trackBy}
+### *ngFor with `trackBy`
+
+If you use `NgFor` with large lists, a small change to one item, such as removing or adding an item, can trigger a cascade of DOM manipulations. For example, re-querying the server could reset a list with all new item objects, even when those items were previously displayed. In this case, Angular sees only a fresh list of new object references and has no choice but to replace the old DOM elements with all new DOM elements.
+
+You can make this more efficient with `trackBy`.
+Add a method to the component that returns the value `NgFor` should track.
+In this case, that value is the hero's `id`. If the `id` has already been rendered,
+Angular keeps track of it and doesn't re-query the server for the same `id`.
+
+<code-example path="built-in-directives/src/app/app.component.ts" region="trackByItems" header="src/app/app.component.ts"></code-example>
+
+In the microsyntax expression, set `trackBy` to the `trackByItems()` method.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="trackBy" header="src/app/app.component.html"></code-example>
+
+Here is an illustration of the `trackBy` effect.
+"Reset items" creates new items with the same `item.id`s.
+"Change ids" creates new items with new `item.id`s.
+
+* With no `trackBy`, both buttons trigger complete DOM element replacement.
+* With `trackBy`, only changing the `id` triggers element replacement.
+
+<div class="lightbox">
+  <img src="generated/images/guide/built-in-directives/ngfor-trackby.gif" alt="Animation of trackBy">
+</div>
+
+
+<div class="alert is-helpful">
+
+Built-in directives use only public APIs; that is,
+they do not have special access to any private APIs that other directives can't access.
+
+</div>
+
+<hr/>
+
+{@a ngSwitch}
+## The `NgSwitch` directives
+
+NgSwitch is like the JavaScript `switch` statement.
+It displays one element from among several possible elements, based on a switch condition.
+Angular puts only the selected element into the DOM.
+<!-- API Flagged -->
+`NgSwitch` is actually a set of three, cooperating directives:
+`NgSwitch`, `NgSwitchCase`, and `NgSwitchDefault` as in the following example.
+
+ <code-example path="built-in-directives/src/app/app.component.html" region="NgSwitch" header="src/app/app.component.html"></code-example>
+
+<div class="lightbox">
+  <img src="generated/images/guide/built-in-directives/ngswitch.gif" alt="Animation of NgSwitch">
+</div>
+
+`NgSwitch` is the controller directive. Bind it to an expression that returns
+the *switch value*, such as `feature`. Though the `feature` value in this
+example is a string, the switch value can be of any type.
+
+**Bind to `[ngSwitch]`**. You'll get an error if you try to set `*ngSwitch` because
+`NgSwitch` is an *attribute* directive, not a *structural* directive.
+Rather than touching the DOM directly, it changes the behavior of its companion directives.
+
+**Bind to `*ngSwitchCase` and `*ngSwitchDefault`**.
+The `NgSwitchCase` and `NgSwitchDefault` directives are _structural_ directives
+because they add or remove elements from the DOM.
+
+* `NgSwitchCase` adds its element to the DOM when its bound value equals the switch value and removes
+its bound value when it doesn't equal the switch value.
+
+* `NgSwitchDefault` adds its element to the DOM when there is no selected `NgSwitchCase`.
+
+The switch directives are particularly useful for adding and removing *component elements*.
+This example switches among four `item` components defined in the `item-switch.components.ts` file.
+Each component has an `item` [input property](guide/inputs-outputs#input "Input property")
+which is bound to the `currentItem` of the parent component.
+
+Switch directives work as well with native elements and web components too.
+For example, you could replace the `<app-best-item>` switch case with the following.
+
+<code-example path="built-in-directives/src/app/app.component.html" region="NgSwitch-div" header="src/app/app.component.html"></code-example>

aio/content/guide/component-interaction.md

@@ -25,7 +25,7 @@ in which two or more components share information.
 ## Pass data from parent to child with input binding
 
 `HeroChildComponent` has two ***input properties***,
-typically adorned with [@Input decorations](guide/template-syntax#inputs-outputs).
+typically adorned with [@Input() decorator](guide/inputs-outputs#input).
 
 
 <code-example path="component-interaction/src/app/hero-child.component.ts" header="component-interaction/src/app/hero-child.component.ts">
@@ -180,7 +180,7 @@ The child component exposes an `EventEmitter` property with which it `emits` eve
 The parent binds to that event property and reacts to those events.
 
 The child's `EventEmitter` property is an ***output property***,
-  typically adorned with an [@Output decoration](guide/template-syntax#inputs-outputs)
+  typically adorned with an [@Output() decorator](guide/inputs-outputs#output)
   as seen in this `VoterComponent`:
 
 

aio/content/guide/creating-libraries.md

@@ -125,7 +125,7 @@ If you've never published a package in npm before, you must create a user accoun
 
 For now, it is not recommended to publish Ivy libraries to NPM because Ivy generated code is not backward compatible with View Engine, so apps using View Engine will not be able to consume them. Furthermore, the internal Ivy instructions are not yet stable, which can potentially break consumers using a different Angular version from the one used to build the library.
 
-When a published library is used in an Ivy app, the Angular CLI will automatically convert it to Ivy using a tool known as the Angular compatibility compiler (`ngcc`). Thus, by publishing your libraries using the View Engine compiler ensures that they can be transparently consumed by both View Engine and Ivy apps.
+When a published library is used in an Ivy app, the Angular CLI will automatically convert it to Ivy using a tool known as the Angular compatibility compiler (`ngcc`). Thus, publishing your libraries using the View Engine compiler ensures that they can be transparently consumed by both View Engine and Ivy apps.
 
 </div>
 

aio/content/guide/dependency-injection-providers.md

@@ -197,11 +197,11 @@ Like  `EvenBetterLogger`, `HeroService` needs to know if the user is authorized
 That authorization can change during the course of a single application session,
 as when you log in a different user.
 
-Let's say you don't want to inject `UserService` directly into `HeroService`, because you don't want to complicate that service with security-sensitive information.
+Imagine that you don't want to inject `UserService` directly into `HeroService`, because you don't want to complicate that service with security-sensitive information.
 `HeroService` won't have direct access to the user information to decide
 who is authorized and who isn't.
 
-To resolve this, we give the `HeroService` constructor a boolean flag to control display of secret heroes.
+To resolve this, give the `HeroService` constructor a boolean flag to control display of secret heroes.
 
 <code-example path="dependency-injection/src/app/heroes/hero.service.ts" region="internals" header="src/app/heroes/hero.service.ts (excerpt)"></code-example>
 
@@ -262,7 +262,7 @@ For example, when bootstrapping an application, you can register many initialize
 
 ```
 export const APP_TOKENS = [
- { provide: PLATFORM_INITIALIZER, useFactory: platformInitialized, multi: true    },
+ { provide: PLATFORM_INITIALIZER, useFactory: platformInitialized, multi: true },
  { provide: APP_INITIALIZER, useFactory: delayBootstrapping, multi: true },
  { provide: APP_BOOTSTRAP_LISTENER, useFactory: appBootstrapped, multi: true },
 ];
@@ -284,6 +284,23 @@ Search for [Constants in API documentation](api?type=const) to find more built-i
 
 </div>
 
+<div class="alert is-helpful">
+
+Note that the reference to the array returned for a `multi` provider is shared between all the
+places where the token is injected. We recommend avoiding mutations of the array (especially for
+predefined tokens) as it may lead to unexpected behavior in other parts of the app that inject
+the same token. You can prevent the value from being mutated by setting its type to `ReadonlyArray`.
+
+</div>
+
+You can use `ReadonlyArray` to type your `multi` provider, so TypeScript triggers an error in case
+of unwanted array mutations:
+
+```
+constructor(@Inject(MULTI_PROVIDER) multiProvider: ReadonlyArray<MultiProvider>) {
+}
+```
+
 {@a tree-shakable-provider}
 {@a tree-shakable-providers}
 

aio/content/guide/deployment.md

@@ -320,7 +320,7 @@ You can dramatically reduce launch time by only loading the application modules
 absolutely must be present when the app starts.
 
 Configure the Angular Router to defer loading of all other modules (and their associated code), either by
-[waiting until the app has launched](guide/router#preloading  "Preloading")
+[waiting until the app has launched](guide/router-tutorial-toh#preloading  "Preloading")
 or by [_lazy loading_](guide/router#lazy-loading "Lazy loading")
 them on demand.
 
@@ -328,7 +328,7 @@ them on demand.
 
 <header>Don't eagerly import something from a lazy-loaded module</header>
 
-If you mean to lazy-load a module, be careful not import it
+If you mean to lazy-load a module, be careful not to import it
 in a file that's eagerly loaded when the app starts (such as the root `AppModule`).
 If you do that, the module will be loaded immediately.
 
@@ -469,7 +469,7 @@ The following configurations determine your requirements.
 
 * TypeScript configuration
 
-   In the TypeScript configuration file, `tsconfig.json`, the "target" option in the `compilerOptions` section determines the ECMAScript target version that the code is compiled to.
+   In the TypeScript configuration file, the "target" option in the `compilerOptions` section determines the ECMAScript target version that the code is compiled to.
    Modern browsers support ES2015 natively, while ES5 is more commonly used to support legacy browsers.
 
 <div class="alert is-helpful">

aio/content/guide/deprecations.md

@@ -490,6 +490,56 @@ If you rely on the behavior that the same object instance should cause change de
 - Clone the resulting value so that it has a new identity.
 - Explicitly call [`ChangeDetectorRef.detectChanges()`](api/core/ChangeDetectorRef#detectchanges) to force the update. 
 
+{@a deprecated-cli-flags}
+## Deprecated CLI APIs and Options
+
+This section contains a complete list all of the currently deprecated CLI flags.
+
+### @angular-devkit/build-angular
+
+| API/Option                      | May be removed in | Notes                                                                           |
+| ------------------------------- | ----------------- |-------------------------------------------------------------------------------- |
+| `i18nFile`                      | <!--v9--> v11     | Specified in the project locale configuration in version 9 and later.           |
+| `i18nFormat`                    | <!--v9--> v11     | Format is now automatically detected.                                           |
+| `i18nLocale`                    | <!--v9--> v11     | New [localization option](/guide/i18n#localize-config) in version 9 and later.  |
+| `lazyModules`                   | <!--v9--> v11     | Used with deprecated SystemJsNgModuleLoader.                                    |
+| `rebaseRootRelativeCssUrls`     | <!--v8--> v11     | Intended only to assist with specific migration issues.                         |
+| `scripts[].lazy`                | <!--v8--> v11     | Renamed to `scripts[].inject`.                                                  |
+| `styles[].lazy`                 | <!--v8--> v11     | Renamed to `styles[].inject`.                                                   |
+| `i18nFormat`                    | <!--v9--> v11     | Renamed to `format` to simplify the user experience.                            |
+| `i18nLocale`                    | <!--v9--> v11     | Redundant with project’s source locale.                                         |
+| `scripts[].lazy`                | <!--v8--> v11     | Renamed to `scripts[].inject`.                                                  |
+| `styles[].lazy`                 | <!--v8--> v11     | Renamed to `styles[].inject`.                                                   |
+| `i18nFile`                      | <!--v9--> v11     | Specified in the project locale configuration in version 9 and later.           |
+| `i18nFormat`                    | <!--v9--> v11     | Format is now automatically detected.                                           |
+| `i18nLocale`                    | <!--v9--> v11     | New [localization option](/guide/i18n#localize-config) in version 9 and later.  |
+| `lazyModules`                   | <!--v9--> v11     | Used with deprecated SystemJsNgModuleLoader.                                    |
+
+### @angular-devkit/core
+
+| API/Option                      | May be removed in | Notes                                                                           |
+| ------------------------------- | ----------------- |-------------------------------------------------------------------------------- |
+| `ModuleNotFoundException`       | <!--v8--> v10     | Not used within projects. Used with Tooling API only. Not Yarn PnP compatible and not used in the Angular CLI. Use Node.js [require.resolve](https://nodejs.org/api/modules.html#modules_require_resolve_request_options).|
+| `resolve`                       | <!--v8--> v10     | Not used within projects. Used with Tooling API only. Not Yarn PnP compatible and not used in the Angular CLI. Use Node.js [require.resolve](https://nodejs.org/api/modules.html#modules_require_resolve_request_options).|
+| `setResolveHook`                | <!--v8--> v10     | Not used within projects. Used with Tooling API only. Not Yarn PnP compatible and not used in the Angular CLI. Use Node.js [require.resolve](https://nodejs.org/api/modules.html#modules_require_resolve_request_options).|
+| `ResolveOptions`                | <!--v8--> v10     | Not used within projects. Used with Tooling API only. Not Yarn PnP compatible and not used in the Angular CLI. Use Node.js [require.resolve](https://nodejs.org/api/modules.html#modules_require_resolve_request_options).|
+| `terminal`                      | <!--v8--> v10     | Unused implementation of terminal codes (color).                                |
+| `isObservable`                  | <!--v8--> v10     | Not used within projects. Used with Tooling API only. Use `isObservable` function from the `rxjs` package.|
+
+### @ngtools/webpack
+
+| API/Option                      | May be removed in | Notes                                                                           |
+| ------------------------------- | ----------------- |-------------------------------------------------------------------------------- |
+| `discoverLazyRoutes`            | <!--v9--> TBD     | Used with deprecated SystemJsNgModuleLoader.                                    |
+| `additionalLazyModules`         | <!--v9--> TBD     | Used with deprecated SystemJsNgModuleLoader.                                    |
+| `additionalLazyModuleResources` | <!--v9--> TBD     | Used with deprecated SystemJsNgModuleLoader.                                    |
+
+### @schematics/angular
+
+| API/Option                      | May be removed in | Notes                                                                           |
+| ------------------------------- | ----------------- |-------------------------------------------------------------------------------- |
+| `entryComponent`                | <!--v9--> TBD     | No longer needed with Ivy.                                                      |
+
 {@a removed}
 ## Removed APIs
 

aio/content/guide/displaying-data.md

@@ -153,14 +153,14 @@ It marks that `<li>` element (and its children) as the "repeater template":
 <div class="alert is-important">
 
 Don't forget the leading asterisk (\*) in `*ngFor`. It is an essential part of the syntax.
-Read more about `ngFor` and `*` in the [ngFor section](guide/template-syntax#ngfor) of the [Template Syntax](guide/template-syntax) page.
+Read more about `ngFor` and `*` in the [ngFor section](guide/built-in-directives#ngfor) of the [Built-in directives](guide/built-in-directives) page.
 
 </div>
 
 Notice the `hero` in the `ngFor` double-quoted instruction;
 it is an example of a template input variable. Read
-more about template input variables in the [microsyntax](guide/template-syntax#microsyntax) section of
-the [Template Syntax](guide/template-syntax) page.
+more about template input variables in the [microsyntax](guide/built-in-directives#microsyntax) section of
+the [Built-in directives](guide/built-in-directives) page.
 
 Angular duplicates the `<li>` for each item in the list, setting the `hero` variable
 to the item (the hero) in the current iteration. Angular uses that variable as the
@@ -255,7 +255,7 @@ To see it in action, add the following paragraph at the bottom of the template:
 <div class="alert is-important">
 
 Don't forget the leading asterisk (\*) in `*ngIf`. It is an essential part of the syntax.
-Read more about `ngIf` and `*` in the [ngIf section](guide/template-syntax#ngIf) of the [Template Syntax](guide/template-syntax) page.
+Read more about `ngIf` and `*` in the [ngIf section](guide/built-in-directives#ngIf) of the [Built-in directives](guide/built-in-directives) page.
 
 </div>
 
@@ -266,7 +266,7 @@ When the component's list of heroes has more than three items, Angular adds the
 to the DOM and the message appears.
 If there are three or fewer items, Angular omits the paragraph, so no message appears.
 
-For more information, see [template expressions](guide/template-syntax#template-expressions).
+For more information, see [template expression operators](guide/interpolation#template-expressions).
 
 
 <div class="alert is-helpful">

aio/content/guide/dynamic-component-loader.md

@@ -131,22 +131,6 @@ The `createComponent()` method returns a reference to the loaded component.
 Use that reference to interact with the component by assigning to its properties or calling its methods.
 
 
-{@a selector-references}
-
-
-#### Selector references
-
-Generally, the Angular compiler generates a `ComponentFactory`
-for any component referenced in a template. However, there are
-no selector references in the templates for
-dynamically loaded components since they load at runtime.
-
-To ensure that the compiler still generates a factory,
-add dynamically loaded components to the `NgModule`'s `entryComponents` array:
-
-<code-example path="dynamic-component-loader/src/app/app.module.ts" region="entry-components" header="src/app/app.module.ts (entry components)"></code-example>
-
-
 
 {@a common-interface}
 

aio/content/guide/elements.md

@@ -117,9 +117,9 @@ The recently-developed [custom elements](https://developer.mozilla.org/en-US/doc
 </tr>
 </table>
 
-In browsers that support Custom Elements natively, the specification requires developers use ES2015 classes to define Custom Elements - developers can opt-in to this by setting the `target: "es2015"` property in their project's `tsconfig.json`. As Custom Element and ES2015 support may not be available in all browsers, developers can instead choose to use a polyfill to support older browsers and ES5 code.
+In browsers that support Custom Elements natively, the specification requires developers use ES2015 classes to define Custom Elements - developers can opt-in to this by setting the `target: "es2015"` property in their project's [TypeScript configuration file](/guide/typescript-configuration). As Custom Element and ES2015 support may not be available in all browsers, developers can instead choose to use a polyfill to support older browsers and ES5 code.
 
-Use the [Angular CLI](cli) to automatically set up your project with the correct polyfill: `ng add @angular/elements --name=*your_project_name*`.
+Use the [Angular CLI](cli) to automatically set up your project with the correct polyfill: `ng add @angular/elements --project=*your_project_name*`.
 - For more information about polyfills, see [polyfill documentation](https://www.webcomponents.org/polyfills).
 
 - For more information about Angular browser support, see [Browser Support](guide/browser-support).
@@ -186,7 +186,7 @@ aDialog.content = 123;  // <-- ERROR: TypeScript knows this should be a string.
 aDialog.body = 'News';  // <-- ERROR: TypeScript knows there is no `body` property on `aDialog`.
 ```
 
-This is a good way to quickly get TypeScript features, such as type checking and autocomplete support, for you custom element. But it can get cumbersome if you need it in several places, because you have to cast the return type on every occurrence.
+This is a good way to quickly get TypeScript features, such as type checking and autocomplete support, for your custom element. But it can get cumbersome if you need it in several places, because you have to cast the return type on every occurrence.
 
 An alternative way, that only requires defining each custom element's type once, is augmenting the `HTMLElementTagNameMap`, which TypeScript uses to infer the type of a returned element based on its tag name (for DOM methods such as `document.createElement()`, `document.querySelector()`, etc.):
 

aio/content/guide/event-binding.md

@@ -0,0 +1,108 @@
+# Event binding `(event)`
+
+Event binding allows you to listen for certain events such as
+keystrokes, mouse movements, clicks, and touches.
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+Angular event binding syntax consists of a **target event** name
+within parentheses on the left of an equal sign, and a quoted
+template statement on the right.
+The following event binding listens for the button's click events, calling
+the component's `onSave()` method whenever a click occurs:
+
+<div class="lightbox">
+  <img src='generated/images/guide/template-syntax/syntax-diagram.svg' alt="Syntax diagram">
+</div>
+
+## Target event
+
+As above, the target is the button's click event.
+
+<code-example path="event-binding/src/app/app.component.html" region="event-binding-1" header="src/app/app.component.html"></code-example>
+
+Alternatively, use the `on-` prefix, known as the canonical form:
+
+<code-example path="event-binding/src/app/app.component.html" region="event-binding-2" header="src/app/app.component.html"></code-example>
+
+Element events may be the more common targets, but Angular looks first to see if the name matches an event property
+of a known directive, as it does in the following example:
+
+<code-example path="event-binding/src/app/app.component.html" region="custom-directive" header="src/app/app.component.html"></code-example>
+
+If the name fails to match an element event or an output property of a known directive,
+Angular reports an “unknown directive” error.
+
+## *$event* and event handling statements
+
+In an event binding, Angular sets up an event handler for the target event.
+
+When the event is raised, the handler executes the template statement.
+The template statement typically involves a receiver, which performs an action
+in response to the event, such as storing a value from the HTML control
+into a model.
+
+The binding conveys information about the event. This information can include data values such as an event object, string, or number named `$event`.
+
+The target event determines the shape of the `$event` object.
+If the target event is a native DOM element event, then `$event` is a
+[DOM event object](https://developer.mozilla.org/en-US/docs/Web/Events),
+with properties such as `target` and `target.value`.
+
+Consider this example:
+
+<code-example path="event-binding/src/app/app.component.html" region="event-binding-3" header="src/app/app.component.html"></code-example>
+
+This code sets the `<input>` `value` property by binding to the `name` property.
+To listen for changes to the value, the code binds to the `input`
+event of the `<input>` element.
+When the user makes changes, the `input` event is raised, and the binding executes
+the statement within a context that includes the DOM event object, `$event`.
+
+To update the `name` property, the changed text is retrieved by following the path `$event.target.value`.
+
+If the event belongs to a directive&mdash;recall that components
+are directives&mdash;`$event` has whatever shape the directive produces.
+
+## Custom events with `EventEmitter`
+
+Directives typically raise custom events with an Angular [EventEmitter](api/core/EventEmitter).
+The directive creates an `EventEmitter` and exposes it as a property.
+The directive calls `EventEmitter.emit(payload)` to fire an event, passing in a message payload, which can be anything.
+Parent directives listen for the event by binding to this property and accessing the payload through the `$event` object.
+
+Consider an `ItemDetailComponent` that presents item information and responds to user actions.
+Although the `ItemDetailComponent` has a delete button, it doesn't know how to delete the hero. It can only raise an event reporting the user's delete request.
+
+Here are the pertinent excerpts from that `ItemDetailComponent`:
+
+<code-example path="event-binding/src/app/item-detail/item-detail.component.html" header="src/app/item-detail/item-detail.component.html (template)" region="line-through"></code-example>
+
+<code-example path="event-binding/src/app/item-detail/item-detail.component.ts" header="src/app/item-detail/item-detail.component.ts (deleteRequest)" region="deleteRequest"></code-example>
+
+The component defines a `deleteRequest` property that returns an `EventEmitter`.
+When the user clicks *delete*, the component invokes the `delete()` method,
+telling the `EventEmitter` to emit an `Item` object.
+
+Now imagine a hosting parent component that binds to the `deleteRequest` event
+of the `ItemDetailComponent`.
+
+<code-example path="event-binding/src/app/app.component.html" header="src/app/app.component.html (event-binding-to-component)" region="event-binding-to-component"></code-example>
+
+When the `deleteRequest` event fires, Angular calls the parent component's
+`deleteItem()` method, passing the *item-to-delete* (emitted by `ItemDetail`)
+in the `$event` variable.
+
+## Template statements have side effects
+
+Though [template expressions](guide/interpolation#template-expressions) shouldn't have [side effects](guide/property-binding#avoid-side-effects), template
+statements usually do. The `deleteItem()` method does have
+a side effect: it deletes an item.
+
+Deleting an item updates the model, and depending on your code, triggers
+other changes including queries and saving to a remote server.
+These changes propagate through the system and ultimately display in this and other views.

aio/content/guide/file-structure.md

@@ -40,7 +40,8 @@ The top level of the workspace contains workspace-wide configuration files, conf
 | `package-lock.json`     | Provides version information for all packages installed into `node_modules` by the npm client. See [npm documentation](https://docs.npmjs.com/files/package-lock.json) for details. If you use the yarn client, this file will be [yarn.lock](https://yarnpkg.com/lang/en/docs/yarn-lock/) instead. |
 | `src/`                  | Source files for the root-level application project. |
 | `node_modules/`         | Provides [npm packages](guide/npm-packages) to the entire workspace. Workspace-wide `node_modules` dependencies are visible to all projects. |
-| `tsconfig.json`         | Default [TypeScript](https://www.typescriptlang.org/) configuration for projects in the workspace. |
+| `tsconfig.json`         | The `tsconfig.json` file is a ["Solution Style"](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-9.html#support-for-solution-style-tsconfigjson-files) TypeScript configuration file. Code editors and TypeScript’s language server use this file to improve development experience. Compilers do not use this file. |
+| `tsconfig.base.json`    | The base [TypeScript](https://www.typescriptlang.org/) configuration for projects in the workspace. All other configuration files inherit from this base file. For more information, see the [Configuration inheritance with extends](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html#configuration-inheritance-with-extends) section of the TypeScript documentation.|
 | `tslint.json`           | Default [TSLint](https://palantir.github.io/tslint/) configuration for projects in the workspace. |
 
 
@@ -54,7 +55,7 @@ This initial root-level application is the *default app* for CLI commands (unles
 
 <div class="alert is-helpful">
 
-   Besides using the CLI on the command line, you can also use an interactive development environment like [Angular Console](https://angularconsole.com/), or manipulate files directly in the app's source folder and configuration files.
+   Besides using the CLI on the command line, you can also manipulate files directly in the app's source folder and configuration files.
 
 </div>
 
@@ -77,6 +78,12 @@ Files at the top level of `src/` support testing and running your application. S
 | `styles.sass`          | Lists CSS files that supply styles for a project. The extension reflects the style preprocessor you have configured for the project. |
 | `test.ts`              | The main entry point for your unit tests, with some Angular-specific configuration. You don't typically need to edit this file. |
 
+<div class="alert is-helpful">
+
+If you create an application using Angular's strict mode, you will also have an additional `package.json` file in the `src/app` directory. For more information, see [Strict mode](/guide/strict-mode).
+
+</div>
+
 {@a app-src}
 
 Inside the `src/` folder, the `app/` folder contains your project's logic and data.
@@ -89,13 +96,14 @@ Angular components, templates, and styles go here.
 | `app/app.component.css`     | Defines the base CSS stylesheet for the root `AppComponent`. |
 | `app/app.component.spec.ts` | Defines a unit test for the root `AppComponent`. |
 | `app/app.module.ts`         | Defines the root module, named `AppModule`, that tells Angular how to assemble the application. Initially declares only the `AppComponent`. As you add more components to the app, they must be declared here. |
+| `app/package.json`              | This file is generated only in applications created using `--strict` mode. This file is not used by package managers. It is used to tell the tools and bundlers whether the code under this directory is free of non-local [side-effects](guide/strict-mode#side-effect). |
 
 ### Application configuration files
 
 The application-specific configuration files for the root application reside at the workspace root level.
 For a multi-project workspace, project-specific configuration files are in the project root, under `projects/project-name/`.
 
-Project-specific [TypeScript](https://www.typescriptlang.org/) configuration files inherit from the workspace-wide `tsconfig.json`, and project-specific [TSLint](https://palantir.github.io/tslint/) configuration files inherit from the workspace-wide `tslint.json`.
+Project-specific [TypeScript](https://www.typescriptlang.org/) configuration files inherit from the workspace-wide `tsconfig.base.json`, and project-specific [TSLint](https://palantir.github.io/tslint/) configuration files inherit from the workspace-wide `tslint.json`.
 
 | APPLICATION-SPECIFIC CONFIG FILES    | PURPOSE |
 | :--------------------- | :------------------------------------------|

aio/content/guide/forms-overview.md

@@ -117,7 +117,7 @@ As users change values and make selections through the view, the new values must
 Similarly, when the program logic changes values in the data model, those values must be reflected in the view.
 
 Reactive and template-driven forms differ in how they handle data flowing from the user or from programmatic changes.
-The following diagrams illustrate both kinds of data flow for each type of form, using the a favorite-color input field defined above.
+The following diagrams illustrate both kinds of data flow for each type of form, using the favorite-color input field defined above.
 
 ### Data flow in reactive forms
 

aio/content/guide/forms.md

@@ -36,7 +36,7 @@ This tutorial teaches you how to do the following:
 * Use `ngModel` to create two-way data bindings for reading and writing input-control values.
 * Provide visual feedback using special CSS classes that track the state of the controls.
 * Display validation errors to users and enable or disable form controls based on the form status.
-* Share information across HTML elements using [template reference variables](guide/template-syntax#template-reference-variables-var).
+* Share information across HTML elements using [template reference variables](guide/template-reference-variables).
 
 ## Prerequisites
 
@@ -93,7 +93,7 @@ In the course of this tutorial, you bind a sample form to data and handle user i
    * Add custom CSS to provide visual feedback on the status.
    * Show and hide validation-error messages.
 4. Respond to a native HTML button-click event by adding to the model data.
-5. Handle form submission using the [`ngSubmit`(api/forms/NgForm#properties)] output property of the form.
+5. Handle form submission using the [`ngSubmit`](api/forms/NgForm#properties) output property of the form.
    * Disable the **Submit** button until the form is valid.
    * After submit, swap out the finished form for different content on the page.
 
@@ -184,7 +184,7 @@ The note reminds you to remove the diagnostic lines when you have finished obser
 
 When you imported the `FormsModule` in your component, Angular automatically created and attached an [NgForm](api/forms/NgForm "API reference for NgForm") directive to the `<form>` tag in the template (because `NgForm` has the selector `form` that matches `<form>` elements).
 
-To get access to the `NgForm` and the overall form status, declare a [template reference variable](guide/template-syntax#template-reference-variables-var).
+To get access to the `NgForm` and the overall form status, declare a [template reference variable](guide/template-reference-variables).
 
 1. Edit the template file `hero-form.component.html`.
 
@@ -467,7 +467,7 @@ You will bind the form property that indicates its overall validity to the **Sub
 3. Run the application now. Notice that the button is enabled&mdash;although
 it doesn't do anything useful yet.
 
-4. Delete the **Name** value. This violates the "required" rule, so it displays the error message&emdash;and notice that it also disables the **Submit** button.
+4. Delete the **Name** value. This violates the "required" rule, so it displays the error message&mdash;and notice that it also disables the **Submit** button.
 
 
    You didn't have to explicitly wire the button's enabled state to the form's validity.

aio/content/guide/glossary.md

@@ -210,6 +210,7 @@ An Angular component class is responsible for exposing data and handling most of
 
 Read more about component classes, templates, and views in [Introduction to Angular concepts](guide/architecture).
 
+
 ## configuration
 
 See  [workspace configuration](#cli-config)
@@ -252,15 +253,15 @@ Data binding is an alternative to manually pushing application data values into
 event listeners, pulling changed values from the screen, and
 updating application data values.
 
-Read about the following forms of binding in [Template Syntax](guide/template-syntax):
+Read about the following forms of binding in Angular's [Template Syntax](guide/template-syntax):
 
- * [Interpolation](guide/template-syntax#interpolation)
- * [Property binding](guide/template-syntax#property-binding)
- * [Event binding](guide/template-syntax#event-binding)
- * [Attribute binding](guide/template-syntax#attribute-binding)
- * [Class binding](guide/template-syntax#class-binding)
- * [Style binding](guide/template-syntax#style-binding)
- * [Two-way data binding with ngModel](guide/template-syntax#ngModel)
+ * [Interpolation](guide/interpolation)
+ * [Property binding](guide/property-binding)
+ * [Event binding](guide/event-binding)
+ * [Attribute binding](guide/attribute-binding)
+ * [Class binding](guide/attribute-binding#class-binding)
+ * [Style binding](guide/attribute-binding#style-binding)
+ * [Two-way data binding with ngModel](guide/built-in-directives#ngModel)
 
 {@a declarable}
 
@@ -472,11 +473,11 @@ Learn more about the injector hierarchy in [Hierarchical Dependency Injectors](g
 ## input
 
 When defining a [directive](#directive), the `@Input()` decorator on a directive property
-makes that property available as a *target* of a [property binding](guide/template-syntax#property-binding).
+makes that property available as a *target* of a [property binding](guide/property-binding).
 Data values flow into an input property from the data source identified
 in the [template expression](#template-expression) to the right of the equal sign.
 
-To learn more, see [input and output properties](guide/template-syntax#inputs-outputs).
+To learn more, see [input and output properties](guide/inputs-outputs).
 
 {@a interpolation}
 
@@ -491,7 +492,7 @@ or displayed between element tags, as in this example.
 ```
 
 
-Read more about [interpolation](guide/template-syntax#interpolation) in [Template Syntax](guide/template-syntax).
+Read more in the [Interpolation](guide/interpolation) guide.
 
 {@a ivy}
 
@@ -578,7 +579,6 @@ Angular calls these hook methods in the following order:
 
 To learn more, see [Lifecycle Hooks](guide/lifecycle-hooks).
 
-
 {@a M}
 
 {@a module}
@@ -653,11 +653,11 @@ An object passed to the `subscribe()` method for an [observable](#observable). T
 ## output
 
 When defining a [directive](#directive), the `@Output{}` decorator on a directive property
-makes that property available as a *target* of [event binding](guide/template-syntax#event-binding).
+makes that property available as a *target* of [event binding](guide/event-binding).
 Events stream *out* of this property to the receiver identified
 in the [template expression](#template-expression) to the right of the equal sign.
 
-To learn more, see [Input and Output Properties](guide/template-syntax#inputs-outputs).
+To learn more, see [Input and Output Properties](guide/inputs-outputs).
 
 
 {@a P}
@@ -732,13 +732,33 @@ The alternative is a [template-driven form](#template-driven-forms).
 When using reactive forms:
 
 * The "source of truth", the form model, is defined in the component class.
-* Validation is set up through validation functions rather than valdation directives.
+* Validation is set up through validation functions rather than validation directives.
 * Each control is explicitly created in the component class by creating a `FormControl` instance manually or with `FormBuilder`.
 * The template input elements do *not* use `ngModel`.
 * The associated Angular directives are prefixed with `form`, such as `formControl`, `formGroup`, and `formControlName`.
 
 The alternative is a template-driven form. For an introduction and comparison of both forms approaches, see [Introduction to Angular Forms](guide/forms-overview).
 
+{@a resolver}
+
+## resolver
+
+A class that implements the [Resolve](api/router/Resolve "API reference") interface (or a function with the same signature as the [resolve() method](api/router/Resolve#resolve "API reference")) that you use to produce or retrieve data that is needed before navigation to a requested route can be completed.
+
+Resolvers run after all [route guards](#route-guard "Definition") for a route tree have been executed and have succeeded.
+
+See an example of using a [resolve guard](guide/router-tutorial-toh#resolve-guard "Routing techniques tutorial") to retrieve dynamic data.
+
+{@a route-guard}
+
+## route guard
+
+A method that controls navigation to a requested route in a routing application.
+Guards determine whether a route can be activated or deactivated, and whether a lazy-loaded module can be loaded.
+
+Learn more in the [Routing and Navigation](guide/router#preventing-unauthorized-access "Examples") guide.
+
+
 {@a router}
 {@a router-module}
 
@@ -917,7 +937,20 @@ The alternative is a reactive form. For an introduction and comparison of both f
 
 A TypeScript-like syntax that Angular evaluates within a [data binding](#data-binding).
 
-Read about how to write template expressions in  [Template expressions](guide/template-syntax#template-expressions).
+Read about how to write template expressions in the [template expressions](guide/interpolation#template-expressions) section of the [Interpolation](guide/interpolation) guide.
+
+{@a template-reference-variable}
+
+## template reference variable
+
+A variable defined in a template that references an instance associated with an element, such as a directive instance, component instance, template as in `TemplateRef`, or DOM element.
+After declaring a template reference variable on an element in a template,
+you can access values from that variable elsewhere within the same template.
+The following example defines a template reference variable named `#phone`.
+
+<code-example path="template-reference-variables/src/app/app.component.html" region="ref-var" header="src/app/app.component.html"></code-example>
+
+For more information, see the [Template reference variable](guide/template-reference-variables) guide.
 
 {@a token}
 
@@ -950,6 +983,10 @@ Many code editors and IDEs support TypeScript either natively or with plug-ins.
 TypeScript is the preferred language for Angular development.
 Read more about TypeScript at [typescriptlang.org](http://www.typescriptlang.org/).
 
+## TypeScript configuration file
+
+A file specifies the root files and the compiler options required to compile a TypeScript project. For more information, see [TypeScript configuration](/guide/typescript-configuration).
+
 
 {@a U}
 

aio/content/guide/http.md

@@ -277,7 +277,7 @@ searchHeroes(term: string): Observable {
   return this.http.jsonp(heroesUrl, 'callback').pipe(
       catchError(this.handleError('searchHeroes', [])) // then handle the error
     );
-};
+}
 ```
 
 This request passes the `heroesURL` as the first parameter and the callback function name as the second parameter.

aio/content/guide/inputs-outputs.md

@@ -0,0 +1,342 @@
+# `@Input()` and `@Output()` properties
+
+`@Input()` and `@Output()` allow Angular to share data between the parent context
+and child directives or components. An `@Input()` property is writable
+while an `@Output()` property is observable.
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+Consider this example of a child/parent relationship:
+
+```html
+<parent-component>
+  <child-component></child-component>
+</parent-component>
+
+```
+
+Here, the `<child-component>` selector, or child directive, is embedded
+within a `<parent-component>`, which serves as the child's context.
+
+`@Input()` and `@Output()` act as
+the API, or application programming interface, of the child
+component in that they allow the child to
+communicate with the parent. Think of `@Input()` and `@Output()` like ports
+or doorways&mdash;`@Input()` is the doorway into the component allowing data
+to flow in while `@Output()` is the doorway out of the component, allowing the
+child component to send data out.
+
+<div class="alert is-helpful">
+
+#### `@Input()` and `@Output()` are independent
+
+Though `@Input()` and `@Output()` often appear together in apps, you can use
+them separately. If the nested
+component is such that it only needs to send data to its parent, you wouldn't
+need an `@Input()`, only an `@Output()`. The reverse is also true in that if the
+child only needs to receive data from the parent, you'd only need `@Input()`.
+
+</div>
+
+{@a input}
+
+## How to use `@Input()`
+
+Use the `@Input()` decorator in a child component or directive to let Angular know
+that a property in that component can receive its value from its parent component.
+It helps to remember that the data flow is from the perspective of the
+child component. So an `@Input()` allows data to be input _into_ the
+child component from the parent component.
+
+
+<div class="lightbox">
+  <img src="generated/images/guide/inputs-outputs/input.svg" alt="Input data flow diagram">
+</div>
+
+To illustrate the use of `@Input()`, edit these parts of your app:
+
+* The child component class and template
+* The parent component class and template
+
+
+### In the child
+
+To use the `@Input()` decorator in a child component class, first import
+`Input` and then decorate the property with `@Input()`:
+
+<code-example path="inputs-outputs/src/app/item-detail/item-detail.component.ts" region="use-input" header="src/app/item-detail/item-detail.component.ts"></code-example>
+
+
+In this case, `@Input()` decorates the property <code class="no-auto-link">item</code>, which has
+a type of `string`, however, `@Input()` properties can have any type, such as
+`number`, `string`, `boolean`, or `object`. The value for `item` will come from the parent component, which the next section covers.
+
+Next, in the child component template, add the following:
+
+<code-example path="inputs-outputs/src/app/item-detail/item-detail.component.html" region="property-in-template" header="src/app/item-detail/item-detail.component.html"></code-example>
+
+
+
+### In the parent
+
+The next step is to bind the property in the parent component's template.
+In this example, the parent component template is `app.component.html`.
+
+First, use the child's selector, here `<app-item-detail>`, as a directive within the
+parent component template. Then, use [property binding](guide/property-binding)
+to bind the property in the child to the property of the parent.
+
+<code-example path="inputs-outputs/src/app/app.component.html" region="input-parent" header="src/app/app.component.html"></code-example>
+
+Next, in the parent component class, `app.component.ts`, designate a value for `currentItem`:
+
+<code-example path="inputs-outputs/src/app/app.component.ts" region="parent-property" header="src/app/app.component.ts"></code-example>
+
+With `@Input()`, Angular passes the value for `currentItem` to the child so that `item` renders as `Television`.
+
+The following diagram shows this structure:
+
+<div class="lightbox">
+  <img src="generated/images/guide/inputs-outputs/input-diagram-target-source.svg" alt="Property binding diagram">
+</div>
+
+The target in the square brackets, `[]`, is the property you decorate
+with `@Input()` in the child component. The binding source, the part
+to the right of the equal sign, is the data that the parent
+component passes to the nested component.
+
+The key takeaway is that when binding to a child component's property in a parent component&mdash;that is, what's
+in square brackets&mdash;you must
+decorate the property with `@Input()` in the child component.
+
+<div class="alert is-helpful">
+
+### `OnChanges` and `@Input()`
+
+To watch for changes on an `@Input()` property, use
+`OnChanges`, one of Angular's [lifecycle hooks](guide/lifecycle-hooks#onchanges).
+`OnChanges` is specifically designed to work with properties that have the
+`@Input()` decorator. See the [`OnChanges`](guide/lifecycle-hooks#onchanges) section of the [Lifecycle Hooks](guide/lifecycle-hooks) guide for more details and examples.
+
+</div>
+
+{@a output}
+
+## How to use `@Output()`
+
+Use the `@Output()` decorator in the child component or directive to allow data to flow from
+the child _out_ to the parent.
+
+An `@Output()` property should normally be initialized to an Angular [`EventEmitter`](api/core/EventEmitter) with values flowing out of the component as [events](guide/event-binding).
+
+
+<div class="lightbox">
+  <img src="generated/images/guide/inputs-outputs/output.svg" alt="Output diagram">
+</div>
+
+Just like with `@Input()`, you can use `@Output()`
+on a property of the child component but its type should be
+`EventEmitter`.
+
+`@Output()` marks a property in a child component as a doorway
+through which data can travel from the child to the parent.
+The child component then has to raise an event so the
+parent knows something has changed. To raise an event,
+`@Output()` works hand in hand with `EventEmitter`,
+which is a class in `@angular/core` that you
+use to emit custom events.
+
+When you use `@Output()`, edit these parts of your app:
+
+* The child component class and template
+* The parent component class and template
+
+
+The following example shows how to set up an `@Output()` in a child
+component that pushes data you enter in an HTML `<input>` to an array in the
+parent component.
+
+<div class="alert is-helpful">
+
+The HTML element `<input>` and the Angular decorator `@Input()`
+are different. This documentation is about component communication in Angular as it pertains to `@Input()` and `@Output()`. For more information on the HTML element `<input>`, see the [W3C Recommendation](https://www.w3.org/TR/html5/sec-forms.html#the-input-element).
+
+</div>
+
+## In the child
+
+This example features an `<input>` where a user can enter a value and click a `<button>` that raises an event. The `EventEmitter` then relays the data to the parent component.
+
+First, be sure to import `Output` and `EventEmitter`
+in the child component class:
+
+```js
+import { Output, EventEmitter } from '@angular/core';
+
+```
+
+Next, still in the child, decorate a property with `@Output()` in the component class.
+The following example `@Output()` is called `newItemEvent` and its type is
+`EventEmitter`, which means it's an event.
+
+
+<code-example path="inputs-outputs/src/app/item-output/item-output.component.ts" region="item-output" header="src/app/item-output/item-output.component.ts"></code-example>
+
+The different parts of the above declaration are as follows:
+
+* `@Output()`&mdash;a decorator function marking the property as a way for data to go from the child to the parent
+* `newItemEvent`&mdash;the name of the `@Output()`
+* `EventEmitter<string>`&mdash;the `@Output()`'s type
+* `new EventEmitter<string>()`&mdash;tells Angular to create a new event emitter and that the data it emits is of type string. The type could be any type, such as `number`, `boolean`, and so on. For more information on `EventEmitter`, see the [EventEmitter API documentation](api/core/EventEmitter).
+
+Next, create an `addNewItem()` method in the same component class:
+
+<code-example path="inputs-outputs/src/app/item-output/item-output.component.ts" region="item-output-class" header="src/app/item-output/item-output.component.ts"></code-example>
+
+The `addNewItem()` function uses the `@Output()`, `newItemEvent`,
+to raise an event in which it emits the value the user
+types into the `<input>`. In other words, when
+the user clicks the add button in the UI, the child lets the parent know
+about the event and gives that data to the parent.
+
+### In the child's template
+
+The child's template has two controls. The first is an HTML `<input>` with a
+[template reference variable](guide/template-reference-variables) , `#newItem`,
+where the user types in an item name. Whatever the user types
+into the `<input>` gets stored in the `#newItem` variable.
+
+<code-example path="inputs-outputs/src/app/item-output/item-output.component.html" region="child-output" header="src/app/item-output/item-output.component.html"></code-example>
+
+The second element is a `<button>`
+with an [event binding](guide/event-binding). You know it's
+an event binding because the part to the left of the equal
+sign is in parentheses, `(click)`.
+
+The `(click)` event is bound to the `addNewItem()` method in the child component class which
+takes as its argument whatever the value of `#newItem` is.
+
+Now the child component has an `@Output()`
+for sending data to the parent and a method for raising an event.
+The next step is in the parent.
+
+## In the parent
+
+In this example, the parent component is `AppComponent`, but you could use
+any component in which you could nest the child.
+
+The `AppComponent` in this example features a list of `items`
+in an array and a method for adding more items to the array.
+
+<code-example path="inputs-outputs/src/app/app.component.ts" region="add-new-item" header="src/app/app.component.ts"></code-example>
+
+The `addItem()` method takes an argument in the form of a string
+and then pushes, or adds, that string to the `items` array.
+
+### In the parent's template
+
+Next, in the parent's template, bind the parent's
+method to the child's event. Put the child selector, here `<app-item-output>`,
+within the parent component's
+template, `app.component.html`.
+
+<code-example path="inputs-outputs/src/app/app.component.html" region="output-parent" header="src/app/app.component.html"></code-example>
+
+The event binding, `(newItemEvent)='addItem($event)'`, tells
+Angular to connect the event in the child, `newItemEvent`, to
+the method in the parent, `addItem()`, and that the event that the child
+is notifying the parent about is to be the argument of `addItem()`.
+In other words, this is where the actual hand off of data takes place.
+The `$event` contains the data that the user types into the `<input>`
+in the child template UI.
+
+Now, in order to see the `@Output()` working, add the following to the parent's template:
+
+```html
+  <ul>
+    <li *ngFor="let item of items">{{item}}</li>
+  </ul>
+  ```
+
+The `*ngFor` iterates over the items in the `items` array. When you enter a value in the child's `<input>` and click the button, the child emits the event and the parent's `addItem()` method pushes the value to the `items` array and it renders in the list.
+
+
+## `@Input()` and `@Output()` together
+
+You can use `@Input()` and `@Output()` on the same child component as in the following:
+
+<code-example path="inputs-outputs/src/app/app.component.html" region="together" header="src/app/app.component.html"></code-example>
+
+The target, `item`, which is an `@Input()` property in the child component class, receives its value from the parent's property, `currentItem`. When you click delete, the child component raises an event, `deleteRequest`, which is the argument for the parent's `crossOffItem()` method.
+
+The following diagram is of an `@Input()` and an `@Output()` on the same
+child component and shows the different parts of each:
+
+<div class="lightbox">
+  <img src="generated/images/guide/inputs-outputs/input-output-diagram.svg" alt="Input/Output diagram">
+</div>
+
+As the diagram shows, use inputs and outputs together in the same manner as using them separately. Here, the child selector is `<app-input-output>` with `item` and `deleteRequest` being `@Input()` and `@Output()`
+properties in the child component class. The property `currentItem` and the method `crossOffItem()` are both in the parent component class.
+
+To combine property and event bindings using the banana-in-a-box
+syntax, `[()]`, see [Two-way Binding](guide/two-way-binding).
+
+## `@Input()` and `@Output()` declarations
+
+Instead of using the `@Input()` and `@Output()` decorators
+to declare inputs and outputs, you can identify
+members in the `inputs` and `outputs` arrays
+of the directive metadata, as in this example:
+
+<code-example path="inputs-outputs/src/app/in-the-metadata/in-the-metadata.component.ts" region="metadata" header="src/app/in-the-metadata/in-the-metadata.component.ts"></code-example>
+
+While declaring `inputs` and `outputs` in the `@Directive` and `@Component`
+metadata is possible, it is a better practice to use the `@Input()` and `@Output()`
+class decorators instead, as follows:
+
+<code-example path="inputs-outputs/src/app/input-output/input-output.component.ts" region="input-output" header="src/app/input-output/input-output.component.ts"></code-example>
+
+See the [Decorate input and output properties](guide/styleguide#decorate-input-and-output-properties) section of the
+[Style Guide](guide/styleguide) for details.
+
+
+
+<div class="alert is-helpful">
+
+If you get a template parse error when trying to use inputs or outputs, but you know that the
+properties do indeed exist, double check
+that your properties are annotated with `@Input()` / `@Output()` or that you've declared
+them in an `inputs`/`outputs` array:
+
+<code-example language="bash">
+Uncaught Error: Template parse errors:
+Can't bind to 'item' since it isn't a known property of 'app-item-detail'
+</code-example>
+
+</div>
+
+{@a aliasing-io}
+
+## Aliasing inputs and outputs
+
+Sometimes the public name of an input/output property should be different from the internal name. While it is a best practice to avoid this situation, Angular does
+offer a solution.
+
+### Aliasing in the metadata
+
+Alias inputs and outputs in the metadata using a colon-delimited (`:`) string with
+the directive property name on the left and the public alias on the right:
+
+<code-example path="inputs-outputs/src/app/aliasing/aliasing.component.ts" region="alias" header="src/app/aliasing/aliasing.component.ts"></code-example>
+
+
+### Aliasing with the `@Input()`/`@Output()` decorator
+
+You can specify the alias for the property name by passing the alias name to the `@Input()`/`@Output()` decorator. The internal name remains as usual.
+
+<code-example path="inputs-outputs/src/app/aliasing/aliasing.component.ts" region="alias-input-output" header="src/app/aliasing/aliasing.component.ts"></code-example>

aio/content/guide/interpolation.md

@@ -0,0 +1,175 @@
+# Interpolation and template expressions
+
+Interpolation allows you to incorporate calculated strings into the text
+between HTML element tags and within attribute assignments. Template
+expressions are what you use to calculate those strings.
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for all of
+the syntax and code snippets in this guide.
+
+</div>
+
+## Interpolation `{{...}}`
+
+Interpolation refers to embedding expressions into marked up text.
+By default, interpolation uses as its delimiter the double curly braces, `{{` and `}}`.
+
+In the following snippet, `{{ currentCustomer }}` is an example of interpolation.
+
+<code-example path="interpolation/src/app/app.component.html" region="interpolation-example1" header="src/app/app.component.html"></code-example>
+
+The text between the braces is often the name of a component
+property. Angular replaces that name with the
+string value of the corresponding component property.
+
+<code-example path="interpolation/src/app/app.component.html" region="component-property" header="src/app/app.component.html"></code-example>
+
+In the example above, Angular evaluates the `title` and `itemImageUrl` properties
+and fills in the blanks, first displaying some title text and then an image.
+
+More generally, the text between the braces is a **template expression**
+that Angular first **evaluates** and then **converts to a string**.
+The following interpolation illustrates the point by adding two numbers:
+
+<code-example path="interpolation/src/app/app.component.html" region="convert-string" header="src/app/app.component.html"></code-example>
+
+The expression can invoke methods of the host component such as `getVal()` in
+the following example:
+
+<code-example path="interpolation/src/app/app.component.html" region="invoke-method" header="src/app/app.component.html"></code-example>
+
+Angular evaluates all expressions in double curly braces,
+converts the expression results to strings, and links them with neighboring literal strings. Finally,
+it assigns this composite interpolated result to an **element or directive property**.
+
+You appear to be inserting the result between element tags and assigning it to attributes.
+However, interpolation is a special syntax that Angular converts into a *property binding*.
+
+<div class="alert is-helpful">
+
+If you'd like to use something other than `{{` and `}}`, you can
+configure the interpolation delimiter via the
+[interpolation](api/core/Component#interpolation)
+option in the `Component` metadata.
+
+</div>
+
+## Template expressions
+
+A template **expression** produces a value and appears within the double
+curly braces, `{{ }}`.
+Angular executes the expression and assigns it to a property of a binding target;
+the target could be an HTML element, a component, or a directive.
+
+The interpolation braces in `{{1 + 1}}` surround the template expression `1 + 1`.
+In the property binding,
+a template expression appears in quotes to the right of the&nbsp;`=` symbol as in `[property]="expression"`.
+
+In terms of syntax, template expressions are similar to JavaScript.
+Many JavaScript expressions are legal template expressions, with a few exceptions.
+
+You can't use JavaScript expressions that have or promote side effects,
+including:
+
+* Assignments (`=`, `+=`, `-=`, `...`)
+* Operators such as `new`, `typeof`, `instanceof`, etc.
+* Chaining expressions with <code>;</code> or <code>,</code>
+* The increment and decrement operators `++` and `--`
+* Some of the ES2015+ operators
+
+Other notable differences from JavaScript syntax include:
+
+* No support for the bitwise operators such as `|` and `&`
+* New [template expression operators](guide/template-expression-operators), such as `|`, `?.` and `!`
+
+
+## Expression context
+
+The *expression context* is typically the _component_ instance.
+In the following snippets, the `recommended` within double curly braces and the
+`itemImageUrl2` in quotes refer to properties of the `AppComponent`.
+
+<code-example path="interpolation/src/app/app.component.html" region="component-context" header="src/app/app.component.html"></code-example>
+
+An expression may also refer to properties of the _template's_ context
+such as a template input variable,
+<!-- link to built-in-directives#template-input-variables -->
+`let customer`, or a template reference variable, `#customerInput`.
+<!-- link to guide/template-ref-variables -->
+
+<code-example path="interpolation/src/app/app.component.html" region="template-input-variable" header="src/app/app.component.html (template input variable)"></code-example>
+
+<code-example path="interpolation/src/app/app.component.html" region="template-reference-variable" header="src/app/app.component.html (template reference variable)"></code-example>
+
+The context for terms in an expression is a blend of the _template variables_,
+the directive's _context_ object (if it has one), and the component's _members_.
+If you reference a name that belongs to more than one of these namespaces,
+the template variable name takes precedence, followed by a name in the directive's _context_,
+and, lastly, the component's member names.
+
+The previous example presents such a name collision. The component has a `customer`
+property and the `*ngFor` defines a `customer` template variable.
+
+<div class="alert is-helpful">
+
+The `customer` in `{{customer.name}}`
+refers to the template input variable, not the component's property.
+
+Template expressions cannot refer to anything in
+the global namespace, except `undefined`. They can't refer to
+`window` or `document`. Additionally, they
+can't call `console.log()` or `Math.max()` and they are restricted to referencing
+members of the expression context.
+
+</div>
+
+## Expression guidelines
+
+When using template expressions follow these guidelines:
+
+* [Simplicity](guide/interpolation#simplicity)
+* [Quick execution](guide/interpolation#quick-execution)
+* [No visible side effects](guide/interpolation#no-visible-side-effects)
+
+### Simplicity
+
+Although it's possible to write complex template expressions, it's a better
+practice to avoid them.
+
+A property name or method call should be the norm, but an occasional Boolean negation, `!`, is OK.
+Otherwise, confine application and business logic to the component,
+where it is easier to develop and test.
+
+### Quick execution
+
+Angular executes template expressions after every change detection cycle.
+Change detection cycles are triggered by many asynchronous activities such as
+promise resolutions, HTTP results, timer events, key presses and mouse moves.
+
+Expressions should finish quickly or the user experience may drag, especially on slower devices.
+Consider caching values when their computation is expensive.
+
+### No visible side effects
+
+A template expression should not change any application state other than the value of the
+target property.
+
+This rule is essential to Angular's "unidirectional data flow" policy.
+You should never worry that reading a component value might change some other displayed value.
+The view should be stable throughout a single rendering pass.
+
+An [idempotent](https://en.wikipedia.org/wiki/Idempotence) expression is ideal because
+it is free of side effects and improves Angular's change detection performance.
+In Angular terms, an idempotent expression always returns
+*exactly the same thing* until one of its dependent values changes.
+
+Dependent values should not change during a single turn of the event loop.
+If an idempotent expression returns a string or a number, it returns the same string or number when called twice in a row. If the expression returns an object, including an `array`, it returns the same object *reference* when called twice in a row.
+
+<div class="alert is-helpful">
+
+There is one exception to this behavior that applies to `*ngFor`. `*ngFor` has `trackBy` functionality that can deal with referential inequality of objects when iterating over them. See [*ngFor with `trackBy`](guide/built-in-directives#ngfor-with-trackby) for details.
+
+</div>

aio/content/guide/ivy-compatibility.md

@@ -2,20 +2,20 @@
 
 The Angular team has worked hard to ensure Ivy is as backwards-compatible with the previous rendering engine ("View Engine") as possible.
 However, in rare cases, minor changes were necessary to ensure that the Angular's behavior was predictable and consistent, correcting issues in the View Engine implementation.
-In order to smooth the transition, we have provided [automated migrations](guide/updating-to-version-9#migrations) wherever possible so your application and library code is migrated automatically by the CLI.
+In order to smooth the transition, we have provided [automated migrations](guide/updating-to-version-10#migrations) wherever possible so your application and library code is migrated automatically by the CLI.
 That said, some applications will likely need to apply some manual updates.
 
 {@a debugging}
 ## How to debug errors with Ivy
 
-In version 9, [a few deprecated APIs have been removed](guide/updating-to-version-9#removals) and there are a [few breaking changes](guide/updating-to-version-9#breaking-changes) unrelated to Ivy.
+In version 10, [a few deprecated APIs have been removed](guide/updating-to-version-10#removals) and there are a [few breaking changes](guide/updating-to-version-10#breaking-changes) unrelated to Ivy.
 If you're seeing errors after updating to version 9, you'll first want to rule those changes out.
 
-To do so, temporarily [turn off Ivy](guide/ivy#opting-out-of-angular-ivy) in your `tsconfig.json` and re-start your app.
+To do so, temporarily [turn off Ivy](guide/ivy#opting-out-of-angular-ivy) in your `tsconfig.base.json` and re-start your app.
 
-If you're still seeing the errors, they are not specific to Ivy. In this case, you may want to consult the [general version 9 guide](guide/updating-to-version-9). If you've opted into any of the stricter type-checking settings that are new with v9, you may also want to check out the [template type-checking guide](guide/template-typecheck).
+If you're still seeing the errors, they are not specific to Ivy. In this case, you may want to consult the [general version 10 guide](guide/updating-to-version-10). If you've opted into any of the new, stricter type-checking settings, you may also want to check out the [template type-checking guide](guide/template-typecheck).
 
-If the errors are gone, switch back to Ivy by removing the changes to the `tsconfig.json` and review the list of expected changes below.
+If the errors are gone, switch back to Ivy by removing the changes to the `tsconfig.base.json` and review the list of expected changes below.
 
 {@a payload-size-debugging}
 ### Payload size debugging

aio/content/guide/lazy-loading-ngmodules.md

@@ -311,7 +311,7 @@ ngOnInit() {
 }
 </code-example>
 
-For more information with a working example, see the [routing tutorial section on preloading](guide/router#preloading-background-loading-of-feature-areas).
+For more information with a working example, see the [routing tutorial section on preloading](guide/router-tutorial-toh#preloading-background-loading-of-feature-areas).
 
 
 <hr>

aio/content/guide/lifecycle-hooks.md

@@ -495,7 +495,7 @@ for one turn of the browser's JavaScript cycle, which triggers a new change-dete
 
 #### Write lean hook methods to avoid performance problems
 
-When you run the *AfterView* sample, notice how frequently Angular calls `AfterViewChecked()`$emdash;often when there are no changes of interest.
+When you run the *AfterView* sample, notice how frequently Angular calls `AfterViewChecked()`-often when there are no changes of interest.
 Be very careful about how much logic or computation you put into one of these methods.
 
 <div class="lightbox">
@@ -569,7 +569,7 @@ which can only be reached by querying for them via the property decorated with
 
 {@a no-unidirectional-flow-worries}
 
-<div class="alert is-helpful>
+<div class="alert is-helpful">
 
 <header>No need to wait for content updates</header>
 

aio/content/guide/migration-solution-style-tsconfig.md

@@ -0,0 +1,55 @@
+# Solution-style `tsconfig.json` migration
+
+## What does this migration do?
+
+This migration adds support to existing projects for TypeScript's new ["solution-style" tsconfig feature](https://devblogs.microsoft.com/typescript/announcing-typescript-3-9/#solution-style-tsconfig).
+
+Support is added by making two changes:
+
+1. Renaming the workspace-level `tsconfig.json` to `tsconfig.base.json`.
+All project [TypeScript configuration files](guide/typescript-configuration) will extend from this base which contains the common options used throughout the workspace.
+
+2. Adding the solution `tsconfig.json` file at the root of the workspace.
+This `tsconfig.json` file will only contain references to project-level TypeScript configuration files and is only used by editors/IDEs.
+
+As an example, the solution `tsconfig.json` for a new project is as follows:
+```json
+// This is a "Solution Style" tsconfig.json file, and is used by editors and TypeScript’s language server to improve development experience.
+// It is not intended to be used to perform a compilation.
+{
+  "files": [],
+  "references": [
+    {
+      "path": "./tsconfig.app.json"
+    },
+    {
+      "path": "./tsconfig.spec.json"
+    },
+    {
+      "path": "./e2e/tsconfig.json"
+    }
+  ]
+}
+```
+
+## Why is this migration necessary?
+
+Solution-style `tsconfig.json` files provide an improved editing experience and fix several long-standing defects when editing files in an IDE.
+IDEs that leverage the TypeScript language service (for example, [Visual Studio Code](https://code.visualstudio.com)), will only use TypeScript configuration files that are named `tsconfig.json`.
+In complex projects, there may be more than one compilation unit and each of these units may have different settings and options.
+
+With the Angular CLI, a project will have application code that will target a browser.
+It will also have unit tests that should not be included within the built application and that also need additional type information present (`jasmine` in this case).
+Both parts of the project also share some but not all of the code within the project.
+As a result, two separate TypeScript configuration files (`tsconfig.app.json` and `tsconfig.spec.json`) are needed to ensure that each part of the application is configured properly and that the right types are used for each part.
+Also if web workers are used within a project, an additional tsconfig (`tsconfig.worker.json`) is needed.
+Web workers use similar but incompatible types to the main browser application.
+This requires the additional configuration file to ensure that the web worker files use the appropriate types and will build successfully.
+
+While the Angular build system knows about all of these TypeScript configuration files, an IDE using TypeScript's language service does not.
+Because of this, an IDE will not be able to properly analyze the code from each part of the project and may generate false errors or make suggestions that are incorrect for certain files.
+By leveraging the new solution-style tsconfig, the IDE can now be aware of the configuration of each part of a project.
+This allows each file to be treated appropriately based on its tsconfig.
+IDE features such as error/warning reporting and auto-suggestion will operate more effectively as well.
+
+The TypeScript 3.9 release [blog post](https://devblogs.microsoft.com/typescript/announcing-typescript-3-9/#solution-style-tsconfig) also contains some additional information regarding this new feature.

aio/content/guide/migration-update-libraries-tslib.md

@@ -0,0 +1,52 @@
+# `tslib` direct dependency migration
+
+## What does this migration do?
+
+If you have any libraries within your workspace, this migration will convert `tslib` peer dependencies to direct dependencies for the libraries.
+TypeScript uses the `tslib` package to provide common helper functions used in compiled TypeScript code.
+The `tslib` version is also updated to `2.0.0` to support TypeScript 3.9.
+
+Before:
+```json
+{
+  "name": "my-lib",
+  "version": "0.0.1",
+  "peerDependencies": {
+    "@angular/common": "^9.0.0",
+    "@angular/core": "^9.0.0",
+    "tslib": "^1.12.0"
+  }
+}
+```
+
+After:
+```json
+{
+  "name": "my-lib",
+  "version": "0.0.1",
+  "peerDependencies": {
+    "@angular/common": "^9.0.0",
+    "@angular/core": "^9.0.0"
+  },
+  "dependencies": {
+    "tslib": "^2.0.0"
+  }
+}
+```
+
+## Why is this migration necessary?
+
+The [`tslib`](https://github.com/Microsoft/tslib) is a runtime library for Typescript.
+The version of this library is bound to the version of the TypeScript compiler used to compile a library.
+Peer dependencies do not accurately represent this relationship between the runtime and the compiler.
+If `tslib` remained declared as a library peer dependency, it would be possible for some Angular workspaces to get into a state where the workspace could not satisfy `tslib` peer dependency requirements for multiple libraries, resulting in build-time or run-time errors.
+
+As of TypeScript 3.9 (used by Angular v10), `tslib` version of 2.x is required to build new applications.
+However, older libraries built with previous version of TypeScript and already published to npm might need `tslib` 1.x.
+This migration makes it possible for code depending on incompatible versions of the `tslib` runtime library to remain interoperable.
+
+
+## Do I still need `tslib` as a dependency in my workspace `package.json`?
+
+Yes.
+The `tslib` dependency declared in the `package.json` file of the workspace is used to build applications within this workspace, as well as run unit tests for workspace libraries, and is required.

aio/content/guide/migration-update-module-and-target-compiler-options.md

@@ -0,0 +1,33 @@
+# Update `module` and `target` compiler options migration
+
+## What does this migration do?
+
+This migration adjusts the [`target`](https://www.typescriptlang.org/v2/en/tsconfig#target) and [`module`](https://www.typescriptlang.org/v2/en/tsconfig#module) settings within the [TypeScript configuration files](guide/typescript-configuration) for the workspace.
+The changes to each option vary based on the builder or command that uses the TypeScript configuration file.
+Unless otherwise noted, changes are only made if the existing value was not changed since the project was created.
+This process helps ensure that intentional changes to the options are kept in place.
+
+TypeScript Configuration File(s) | Changed Property | Existing Value | New Value
+------------- | ------------- | ------------- | ------------- | -------------
+`<workspace base>/tsconfig.base.json` | `"module"` | `"esnext"` | `"es2020"`
+Used in `browser` builder options (`ng build` for applications) | `"module"` | `"esnext"` | `"es2020"`
+Used in `ng-packgr` builder options (`ng build` for libraries) | `"module"` | `"esnext"` | `"es2020"`
+Used in `karma` builder options (`ng test` for applications) | `"module"` | `"esnext"` | `"es2020"`
+Used in `server` builder options (universal) | `"module"` | `"commonjs"` | _removed_
+Used in `server` builder options (universal) | `"target"` | _any_ | `"es2016"`
+Used in `protractor` builder options (`ng e2e` for applications) | `"target"` | `"es5"` | `"es2018"`
+
+## Why is this migration necessary?
+
+This migration provides improvements to the long-term supportability of projects by updating the projects to use recommended best practice compilation options.
+
+For the functionality that executes on Node.js, such as Universal and Protractor, the new settings provide performance and troubleshooting benefits as well.
+The minimum Node.js version for the Angular CLI (v10.13) supports features in ES2018 and earlier.
+By targeting later ES versions, the compiler transforms less code and can use newer features directly.
+Since zone.js does not support native `async` and `await`, the universal builds still target ES2016.
+
+## Why `"es2020"` instead of `"esnext"`?
+
+In TypeScript 3.9, the behavior of the TypeScript compiler controlled by `module` is the same with both `"esnext"` and `"es2020"` values.
+This behavior can change in the future, because the `"esnext"` option could evolve in a backwards incompatible ways, resulting in build-time or run-time errors during a TypeScript update.
+As a result, code can become unstable. Using the `"es2020"` option mitigates this risk.

aio/content/guide/module-types.md

@@ -1,116 +1,41 @@
-# Types of feature modules
+# Guidelines for creating NgModules
 
-There are five general categories of feature modules which
-tend to fall into the following groups:
+This topic provides a conceptual overview of the different categories of [NgModules](guide/glossary#ngmodule "Definition of NgModule") you can create in order to organize your code in a modular structure.
+These categories are not cast in stone—they are suggestions.
+You may want to create NgModules for other purposes, or combine the characteristics of some of these categories.
 
-* Domain feature modules.
-* Routed feature modules.
-* Routing modules.
-* Service feature modules.
-* Widget feature modules.
+NgModules are a great way to organize an app and keep code related to a specific functionality or feature separate from other code.
+Use NgModules to consolidate [components](guide/glossary#component "Definition of component"), [directives](guide/glossary#directive "Definition of directive"), and [pipes](guide/glossary#pipe "Definition of pipe)") into cohesive blocks of functionality.
+Focus each block on a feature or business domain, a workflow or navigation flow, a common collection of utilities, or one or more [providers](guide/glossary#provider "Definition of provider") for [services](guide/glossary#service "Definition of service").
 
-While the following guidelines describe the use of each type and their
-typical characteristics, in real world apps, you may see hybrids.
+For more about NgModules, see [Organizing your app with NgModules](guide/ngmodules "Organizing your app with NgModules").
 
-<table>
+<div class="alert is-helpful">
 
- <tr>
-   <th style="vertical-align: top">
-     Feature Module
-   </th>
+For the example app used in NgModules-related topics, see the <live-example name="ngmodules"></live-example>.
 
-   <th style="vertical-align: top">
-     Guidelines
-   </th>
- </tr>
+</div>
 
- <tr>
-   <td>Domain</td>
-   <td>
-     Domain feature modules deliver a user experience dedicated to a particular application domain like editing a customer or placing an order.
+## Summary of NgModule categories
 
-     They typically have a top component that acts as the feature root and private, supporting sub-components descend from it.
+All apps start by [bootstrapping a root NgModule](guide/bootstrapping "Launching an app with a root NgModule").
+You can organize your other NgModules any way you wish.
 
-     Domain feature modules consist mostly of declarations. Only the top component is exported.
+This topic provides some guidelines for the following general categories of NgModules:
 
-     Domain feature modules rarely have providers. When they do, the lifetime of the provided services should be the same as the lifetime of the module.
+* [Domain](#domain): A domain NgModule is organized around a feature, business domain, or user experience.
+* [Routed](#routed): The top component of the NgModule acts as the destination of a [router](guide/glossary#router "Definition of router") navigation route.
+* [Routing](#routing): A routing NgModule provides the routing configuration for another NgModule.
+* [Service](#service): A service NgModule provides utility services such as data access and messaging.
+* [Widget](#widget): A widget NgModule makes a component, directive, or pipe available to other NgModules.
+* [Shared](#shared): A shared NgModule makes a set of components, directives, and pipes available to other NgModules.
 
-     Domain feature modules are typically imported exactly once by a larger feature module.
-
-     They might be imported by the root `AppModule` of a small application that lacks routing.
-   </td>
- </tr>
- <tr>
-   <td>Routed</td>
-   <td>
-     Routed feature modules are domain feature modules whose top components are the targets of router navigation routes.
-
-     All lazy-loaded modules are routed feature modules by definition.
-
-     Routed feature modules don’t export anything because their components never appear in the template of an external component.
-
-     A lazy-loaded routed feature module should not be imported by any module. Doing so would trigger an eager load, defeating the purpose of lazy loading.That means you won’t see them mentioned among the `AppModule` imports. An eager loaded routed feature module must be imported by another module so that the compiler learns about its components.
-
-     Routed feature modules rarely have providers for reasons explained in [Lazy Loading Feature Modules](/guide/lazy-loading-ngmodules). When they do, the lifetime of the provided services should be the same as the lifetime of the module. Don't provide application-wide singleton services in a routed feature module or in a module that the routed module imports.
-   </td>
- </tr>
-
- <tr>
-   <td>Routing</td>
-   <td>
-
-     A routing module provides routing configuration for another module and separates routing concerns from its companion module.
-
-     A routing module typically does the following:
-
-     <ul>
-     <li>Defines routes.</li>
-     <li>Adds router configuration to the module's imports.</li>
-     <li>Adds guard and resolver service providers to the module's providers.</li>
-     <li>The name of the routing module should parallel the name of its companion module, using the suffix "Routing". For example, <code>FooModule</code> in <code>foo.module.ts</code> has a routing module named <code>FooRoutingModule</code> in <code>foo-routing.module.ts</code>. If the companion module is the root <code>AppModule</code>, the <code>AppRoutingModule</code> adds router configuration to its imports with <code>RouterModule.forRoot(routes)</code>. All other routing modules are children that import <code>RouterModule.forChild(routes)</code>.</li>
-     <li>A routing module re-exports the <code>RouterModule</code> as a convenience so that components of the companion module have access to router directives such as <code>RouterLink</code> and <code>RouterOutlet</code>.</li>
-     <li>A routing module does not have its own declarations. Components, directives, and pipes are the responsibility of the feature module, not the routing module.</li>
-     </ul>
-
-     A routing module should only be imported by its companion module.
-
-   </td>
- </tr>
-
- <tr>
-   <td>Service</td>
-   <td>
-
-     Service modules provide utility services such as data access and messaging. Ideally, they consist entirely of providers and have no declarations. Angular's `HttpClientModule` is a good example of a service module.
-
-     The root `AppModule` is the only module that should import service modules.
-
-   </td>
- </tr>
-
- <tr>
-   <td>Widget</td>
-   <td>
-
-     A widget module makes components, directives, and pipes available to external modules. Many third-party UI component libraries are widget modules.
-
-     A widget module should consist entirely of declarations, most of them exported.
-
-     A widget module should rarely have providers.
-
-     Import widget modules in any module whose component templates need the widgets.
-
-   </td>
- </tr>
-
-</table>
-
-The following table summarizes the key characteristics of each feature module group.
+The following table summarizes the key characteristics of each category.
 
 <table>
  <tr>
    <th style="vertical-align: top">
-     Feature Module
+     NgModule
    </th>
 
    <th style="vertical-align: top">
@@ -135,7 +60,7 @@ The following table summarizes the key characteristics of each feature module gr
    <td>Yes</td>
    <td>Rare</td>
    <td>Top component</td>
-   <td>Feature, AppModule</td>
+   <td>Another domain, AppModule</td>
  </tr>
 
  <tr>
@@ -151,7 +76,7 @@ The following table summarizes the key characteristics of each feature module gr
    <td>No</td>
    <td>Yes (Guards)</td>
    <td>RouterModule</td>
-   <td>Feature (for routing)</td>
+   <td>Another domain (for routing)</td>
  </tr>
 
  <tr>
@@ -167,14 +92,137 @@ The following table summarizes the key characteristics of each feature module gr
    <td>Yes</td>
    <td>Rare</td>
    <td>Yes</td>
-   <td>Feature</td>
+   <td>Another domain</td>
+ </tr>
+
+ <tr>
+   <td>Shared</td>
+   <td>Yes</td>
+   <td>No</td>
+   <td>Yes</td>
+   <td>Another domain</td>
  </tr>
 </table>
 
-<hr />
+{@a domain}
 
-## More on NgModules
+## Domain NgModules
+
+Use a domain NgModule to deliver a user experience dedicated to a particular feature or app domain, such as editing a customer or placing an order.
+One example is `ContactModule` in the <live-example name="ngmodules"></live-example>.
+
+A domain NgModule organizes the code related to a certain function, containing all of the components, routing, and templates that make up the function.
+Your top component in the domain NgModule acts as the feature or domain's root, and is the only component you export.
+Private supporting subcomponents descend from it.
+
+Import a domain NgModule exactly once into another NgModule, such as a domain NgModule, or into the root NgModule (`AppModule`) of an app that contains only a few NgModules.
+
+Domain NgModules consist mostly of declarations.
+You rarely include providers.
+If you do, the lifetime of the provided services should be the same as the lifetime of the NgModule.
+
+<div class="alert is-helpful">
+
+For more information about lifecycles, see [Hooking into the component lifecycle](guide/lifecycle-hooks "Hooking into the component lifecycle").
+
+</div>
+
+{@a routed}
+
+## Routed NgModules
+
+Use a routed NgModule for all [lazy-loaded NgModules](guide/lazy-loading-ngmodules "Lazy-loading an NgModule").
+Use the top component of the NgModule as the destination of a router navigation route.
+Routed NgModules don’t export anything because their components never appear in the template of an external component.
+
+Don't import a lazy-loaded routed NgModule into another NgModule, as this would trigger an eager load, defeating the purpose of lazy loading.
+
+Routed NgModules rarely have providers because you load a routed NgModule only when needed (such as for routing).
+Services listed in the NgModules' `provider` array would not be available because the root injector wouldn’t know about the lazy-loaded NgModule.
+If you include providers, the lifetime of the provided services should be the same as the lifetime of the NgModule.
+Don't provide app-wide [singleton services](guide/singleton-services) in a routed NgModule or in an NgModule that the routed NgModule imports.
+
+<div class="alert is-helpful">
+
+For more information about providers and lazy-loaded routed NgModules, see [Limiting provider scope](guide/providers#limiting-provider-scope-by-lazy-loading-modules "Providing dependencies: Limiting provider scope").
+
+</div>
+
+{@a routing}
+
+## Routing NgModules
+
+Use a routing NgModule to provide the routing configuration for a domain NgModule, thereby separating routing concerns from its companion domain NgModule.
+One example is `ContactRoutingModule` in the <live-example name="ngmodules"></live-example>, which provides the routing for its companion domain NgModule `ContactModule`.
+
+<div class="alert is-helpful">
+
+For an overview and details about routing, see [In-app navigation: routing to views](guide/router "In-app navigation: routing to views").
+
+</div>
+
+Use a routing NgModule to do the following tasks:
+
+* Define routes.
+* Add router configuration to the NgModule's import.
+* Add guard and resolver service providers to the NgModule's providers.
+
+The name of the routing NgModule should parallel the name of its companion NgModule, using the suffix `Routing`.
+For example, <code>ContactModule</code> in <code>contact.module.ts</code> has a routing NgModule named <code>ContactRoutingModule</code> in <code>contact-routing.module.ts</code>.
+
+Import a routing NgModule only into its companion NgModule.
+If the companion NgModule is the root <code>AppModule</code>, the <code>AppRoutingModule</code> adds router configuration to its imports with <code>RouterModule.forRoot(routes)</code>.
+All other routing NgModules are children that import <code>RouterModule.forChild(routes)</code>.
+
+In your routing NgModule, re-export the <code>RouterModule</code> as a convenience so that components of the companion NgModule have access to router directives such as <code>RouterLink</code> and <code>RouterOutlet</code>.
+
+Don't use declarations in a routing NgModule.
+Components, directives, and pipes are the responsibility of the companion domain NgModule, not the routing NgModule.
+
+{@a service}
+
+## Service NgModules
+
+Use a service NgModule to provide a utility service such as data access or messaging.
+Ideal service NgModules consist entirely of providers and have no declarations.
+Angular's `HttpClientModule` is a good example of a service NgModule.
+
+Use only the root `AppModule` to import service NgModules.
+
+{@a widget}
+
+## Widget NgModules
+
+Use a widget NgModule to make a component, directive, or pipe available to external NgModules.
+Import widget NgModules into any NgModules that need the widgets in their templates.
+Many third-party UI component libraries are provided as widget NgModules.
+
+A widget NgModule should consist entirely of declarations, most of them exported.
+It would rarely have providers.
+
+{@a shared}
+
+## Shared NgModules
+
+Put commonly used directives, pipes, and components into one NgModule, typically named `SharedModule`, and then import just that NgModule wherever you need it in other parts of your app.
+You can import the shared NgModule in your domain NgModules, including [lazy-loaded NgModules](guide/lazy-loading-ngmodules "Lazy-loading an NgModule").
+One example is `SharedModule` in the <live-example name="ngmodules"></live-example>, which provides the `AwesomePipe` custom pipe and `HighlightDirective` directive.
+
+Shared NgModules should not include providers, nor should any of its imported or re-exported NgModules include providers.
+
+To learn how to use shared modules to organize and streamline your code, see [Sharing NgModules in an app](guide/sharing-ngmodules "Sharing NgModules in an app").
+
+## Next steps
 
 You may also be interested in the following:
-* [Lazy Loading Modules with the Angular Router](guide/lazy-loading-ngmodules).
-* [Providers](guide/providers).
+
+* For more about NgModules, see [Organizing your app with NgModules](guide/ngmodules "Organizing your app with NgModules").
+* To learn more about the root NgModule, see [Launching an app with a root NgModule](guide/bootstrapping "Launching an app with a root NgModule").
+* To learn about frequently used Angular NgModules and how to import them into your app, see [Frequently-used modules](guide/frequent-ngmodules "Frequently-used modules").
+* For a complete description of the NgModule metadata properties, see [Using the NgModule metadata](guide/ngmodule-api "Using the NgModule metadata").
+
+If you want to manage NgModule loading and the use of dependencies and services, see the following:
+
+* To learn about loading NgModules eagerly when the app starts, or lazy-loading NgModules asynchronously by the router, see [Lazy-loading feature modules](guide/lazy-loading-ngmodules).
+* To understand how to provide a service or other dependency for your app, see [Providing Dependencies for an NgModule](guide/providers "Providing Dependencies for an NgModule").
+* To learn how to create a singleton service to use in NgModules, see [Making a service a singleton](guide/singleton-services "Making a service a singleton").

aio/content/guide/ngmodule-vs-jsmodule.md

@@ -1,72 +1,82 @@
 # JavaScript modules vs. NgModules
 
-JavaScript and Angular use modules to organize code, and
-though they organize it differently, Angular apps rely on both.
+JavaScript modules and NgModules can help you modularize your code, but they are very different.
+Angular apps rely on both kinds of modules.
 
+## JavaScript modules: Files containing code
 
-## JavaScript modules
+A [JavaScript module](https://javascript.info/modules "JavaScript.Info - Modules") is an individual file with JavaScript code, usually containing a class or a library of functions for a specific purpose within your app.
+JavaScript modules let you spread your work across multiple files.
 
-In JavaScript, modules are individual files with JavaScript code in them. To make what’s in them available, you write an export statement, usually after the relevant code, like this:
+<div class="alert is-helpful">
+
+To learn more about JavaScript modules, see [ES6 In Depth: Modules](https://hacks.mozilla.org/2015/08/es6-in-depth-modules/).
+For the module specification, see the [6th Edition of the ECMAScript standard](http://www.ecma-international.org/ecma-262/6.0/#sec-modules).
+
+</div>
+
+To make the code in a JavaScript module available to other modules, use an `export` statement at the end of the relevant code in the module, such as the following:
 
 ```typescript
 export class AppComponent { ... }
 ```
 
-Then, when you need that file’s code in another file, you import it like this:
+When you need that module’s code in another module, use an `import` statement as follows:
 
 ```typescript
 import { AppComponent } from './app.component';
 ```
 
-JavaScript modules help you namespace, preventing accidental global variables.
+Each module has its own top-level scope.
+In other words, top-level variables and functions in a module are not seen in other scripts or modules.
+Each module provides a namespace for identifiers to prevent them from clashing with identifiers in other modules.
+With multiple modules, you can prevent accidental global variables by creating a single global namespace and adding sub-modules to it.
 
-For more information on JavaScript modules, see [JavaScript/ECMAScript modules](https://hacks.mozilla.org/2015/08/es6-in-depth-modules/).
+The Angular framework itself is loaded as a set of JavaScript modules.
 
-## NgModules
+## NgModules: Classes with metadata for compiling
 
-<!-- KW-- perMisko: let's discuss. This does not answer the question why it is different. Also, last sentence is confusing.-->
-NgModules are classes decorated with `@NgModule`. The `@NgModule` decorator’s `imports` array tells Angular what other NgModules the current module needs. The modules in the `imports` array are different than JavaScript modules because they are NgModules rather than regular JavaScript modules. Classes with an `@NgModule` decorator are by convention kept in their own files, but what makes them an `NgModule` isn’t being in their own file, like JavaScript modules; it’s the presence of `@NgModule` and its metadata.
+An [NgModule](guide/glossary#ngmodule "Definition of NgModule") is a class marked by the `@NgModule` decorator with a metadata object that describes how that particular part of the app fits together with the other parts.
+NgModules are specific to Angular.
+While classes with an `@NgModule` decorator are by convention kept in their own files, they differ from JavaScript modules because they include this metadata.
 
-The `AppModule` generated from the [Angular CLI](cli) demonstrates both kinds of modules in action:
+The `@NgModule` metadata plays an important role in guiding the Angular compilation process that converts the app code you write into highly performant JavaScript code.
+The metadata describes how to compile a component's template and how to create an [injector](guide/glossary#injector "Definition of injector") at runtime.
+It identifies the NgModule's [components](guide/glossary#component "Definition of component"), [directives](guide/glossary#directive "Definition of directive"), and [pipes](guide/glossary#pipe "Definition of pipe)"),
+and makes some of them public through the `exports` property so that external components can use them.
+You can also use an NgModule to add [providers](guide/glossary#provider "Definition of provider") for [services](guide/glossary#service "Definition of a service"), so that the services are available elsewhere in your app.
 
-```typescript
-/* These are JavaScript import statements. Angular doesn’t know anything about these. */
-import { BrowserModule } from '@angular/platform-browser';
-import { NgModule } from '@angular/core';
+Rather than defining all member classes in one giant file as a JavaScript module, declare which components, directives, and pipes belong to the NgModule in the `@NgModule.declarations` list.
+These classes are called [declarables](guide/glossary#declarable "Definition of a declarable").
+An NgModule can export only the declarable classes it owns or imports from other NgModules.
+It doesn't declare or export any other kind of class.
+Declarables are the only classes that matter to the Angular compilation process.
 
-import { AppComponent } from './app.component';
+For a complete description of the NgModule metadata properties, see [Using the NgModule metadata](guide/ngmodule-api "Using the NgModule metadata").
 
-/* The @NgModule decorator lets Angular know that this is an NgModule. */
-@NgModule({
-  declarations: [
-    AppComponent
-  ],
-  imports: [     /* These are NgModule imports. */
-    BrowserModule
-  ],
-  providers: [],
-  bootstrap: [AppComponent]
-})
-export class AppModule { }
-```
+## An example that uses both
 
+The root NgModule `AppModule` generated by the [Angular CLI](cli) for a new app project demonstrates how you use both kinds of modules:
 
-The NgModule classes differ from JavaScript module in the following key ways:
+<code-example path="ngmodules/src/app/app.module.1.ts" header="src/app/app.module.ts (default AppModule)"></code-example>
 
-* An NgModule bounds [declarable classes](guide/ngmodule-faq#q-declarable) only.
-Declarables are the only classes that matter to the [Angular compiler](guide/ngmodule-faq#q-angular-compiler).
-* Instead of defining all member classes in one giant file as in a JavaScript module,
-you list the module's classes in the `@NgModule.declarations` list.
-* An NgModule can only export the [declarable classes](guide/ngmodule-faq#q-declarable)
-it owns or imports from other modules. It doesn't declare or export any other kind of class.
-* Unlike JavaScript modules, an NgModule can extend the _entire_ application with services
-by adding providers to the `@NgModule.providers` list.
+The root NgModule starts with `import` statements to import JavaScript modules.
+It then configures the `@NgModule` with the following arrays:
 
-<hr />
+* `declarations`: The components, directives, and pipes that belong to the NgModule.
+  A new app project's root NgModule has only one component, called `AppComponent`.
 
-## More on NgModules
+* `imports`: Other NgModules you are using, so that you can use their declarables.
+  The newly generated root NgModule imports [`BrowserModule`](api/platform-browser/BrowserModule "BrowserModule NgModule") in order to use browser-specific services such as [DOM](https://www.w3.org/TR/DOM-Level-2-Core/introduction.html "Definition of Document Object Model") rendering, sanitization, and location.
 
-For more information on NgModules, see:
-* [Bootstrapping](guide/bootstrapping).
-* [Frequently used modules](guide/frequent-ngmodules).
-* [Providers](guide/providers).
+* `providers`: Providers of services that components in other NgModules can use.
+  There are no providers in a newly generated root NgModule.
+
+* `bootstrap`: The [entry component](guide/entry-components "Specifying an entry component") that Angular creates and inserts into the `index.html` host web page, thereby bootstrapping the app.
+  This entry component, `AppComponent`, appears in both the `declarations` and the `bootstrap` arrays.
+
+## Next steps
+
+* For more about NgModules, see [Organizing your app with NgModules](guide/ngmodules "Organizing your app with NgModules").
+* To learn more about the root NgModule, see [Launching an app with a root NgModule](guide/bootstrapping "Launching an app with a root NgModule").
+* To learn about frequently used Angular NgModules and how to import them into your app, see [Frequently-used modules](guide/frequent-ngmodules "Frequently-used modules").

aio/content/guide/npm-packages.md

@@ -118,7 +118,6 @@ Package name                               | Description
 [**@angular&#8209;devkit/<br />build&#8209;angular**](https://github.com/angular/angular-cli/) | The Angular build tools.
 [**@angular/cli**](https://github.com/angular/angular-cli/) | The Angular CLI tools.
 **@angular/<br />compiler&#8209;cli** | The Angular compiler, which is invoked by the Angular CLI's `ng build` and `ng serve` commands.
-**@angular/<br />language&#8209;service** | The [Angular language service](guide/language-service) analyzes component templates and provides type and error information that TypeScript-aware editors can use to improve the developer's experience. For example, see the [Angular language service extension for VS Code](https://marketplace.visualstudio.com/items?itemName=Angular.ng-template).
 **@types/... ** | TypeScript definition files for 3rd party libraries such as Jasmine and Node.js.
 [**codelyzer**](https://www.npmjs.com/package/codelyzer) | A linter for Angular apps whose rules conform to the Angular [style guide](guide/styleguide).
 **jasmine/... ** | Packages to support the [Jasmine](https://jasmine.github.io/) test library.
@@ -135,3 +134,4 @@ Package name                               | Description
 
  * [Building and serving](guide/build) describes how packages come together to create a development build.
  * [Deployment](guide/deployment) describes how packages come together to create a production build.
+ 

aio/content/guide/observables-in-angular.md

@@ -2,13 +2,13 @@
 
 Angular makes use of observables as an interface to handle a variety of common asynchronous operations. For example:
 
-* You can define [custom events](guide/template-syntax#custom-events-with-eventemitter) that send observable output data from a child to a parent component.
+* You can define [custom events](guide/event-binding#custom-events-with-eventemitter) that send observable output data from a child to a parent component.
 * The HTTP module uses observables to handle AJAX requests and responses.
 * The Router and Forms modules use observables to listen for and respond to user-input events.
 
 ## Transmitting data between components
 
-Angular provides an `EventEmitter` class that is used when publishing values from a component through the [`@Output()` decorator](guide/template-syntax#how-to-use-output).
+Angular provides an `EventEmitter` class that is used when publishing values from a component through the [`@Output()` decorator](guide/inputs-outputs#how-to-use-output).
 `EventEmitter` extends [RxJS `Subject`](https://rxjs.dev/api/index/class/Subject), adding an `emit()` method so it can send arbitrary values.
 When you call `emit()`, it passes the emitted value to the `next()` method of any subscribed observer.
 

aio/content/guide/observables.md

@@ -112,7 +112,7 @@ Because observables produce values asynchronously, try/catch will not effectivel
 <code-example>
 myObservable.subscribe({
   next(num) { console.log('Next num: ' + num)},
-  error(err) { console.log('Received an errror: ' + err)}
+  error(err) { console.log('Received an error: ' + err)}
 });
 </code-example>
 

aio/content/guide/pipes.md

@@ -1,607 +1,440 @@
-# Pipes
+# Transforming Data Using Pipes
 
-Every application starts out with what seems like a simple task: get data, transform them, and show them to users.
-Getting data could be as simple as creating a local variable or as complex as streaming data over a WebSocket.
+Use [pipes](guide/glossary#pipe "Definition of a pipe") to transform strings, currency amounts, dates, and other data for display.
+Pipes are simple functions you can use in [template expressions](/guide/glossary#template-expression "Definition of template expression") to accept an input value and return a transformed value. Pipes are useful because you can use them throughout your application, while only declaring each pipe once.
+For example, you would use a pipe to show a date as **April 15, 1988** rather than the raw string format.
 
 <div class="alert is-helpful">
 
-  For the sample app that this page describes, see the <live-example></live-example>.
+  For the sample app used in this topic, see the <live-example></live-example>.
 
 </div>
 
-Once data arrives, you could push their raw `toString` values directly to the view,
-but that rarely makes for a good user experience.
-For example, in most use cases, users prefer to see a date in a simple format like
-<samp>April 15, 1988</samp> rather than the raw string format
-<samp>Fri Apr 15 1988 00:00:00 GMT-0700 (Pacific Daylight Time)</samp>.
-
-Clearly, some values benefit from a bit of editing. You may notice that you
-desire many of the same transformations repeatedly, both within and across many applications.
-You can almost think of them as styles.
-In fact, you might like to apply them in your HTML templates as you do styles.
-
-Introducing Angular pipes, a way to write display-value transformations that you can declare in your HTML.
-
-
-## Using pipes
-
-A pipe takes in data as input and transforms it to a desired output.
-In this page, you'll use pipes to transform a component's birthday property into
-a human-friendly date.
-
-
-<code-example path="pipes/src/app/hero-birthday1.component.ts" header="src/app/hero-birthday1.component.ts"></code-example>
-
-
-
-Focus on the component's template.
-
-
-<code-example path="pipes/src/app/app.component.html" region="hero-birthday-template" header="src/app/app.component.html"></code-example>
-
-
-
-Inside the interpolation expression, you flow the component's `birthday` value through the
-[pipe operator](guide/template-syntax#pipe) ( | ) to the [Date pipe](api/common/DatePipe)
-function on the right. All pipes work this way.
-
-
-
-
-## Built-in pipes
-Angular comes with a stock of pipes such as
-`DatePipe`, `UpperCasePipe`, `LowerCasePipe`, `CurrencyPipe`, and `PercentPipe`.
-They are all available for use in any template.
+Angular provides built-in pipes for typical data transformations, including transformations for internationalization (i18n), which use locale information to format data.
+The following are commonly used built-in pipes for data formatting:
 
+* [`DatePipe`](api/common/DatePipe): Formats a date value according to locale rules.
+* [`UpperCasePipe`](api/common/UpperCasePipe): Transforms text to all upper case.
+* [`LowerCasePipe`](api/common/LowerCasePipe): Transforms text to all lower case.
+* [`CurrencyPipe`](api/common/CurrencyPipe): Transforms a number to a currency string, formatted according to locale rules.
+* [`DecimalPipe`](/api/common/DecimalPipe): Transforms a number into a string with a decimal point, formatted according to locale rules.
+* [`PercentPipe`](api/common/PercentPipe): Transforms a number to a percentage string, formatted according to locale rules.
 
 <div class="alert is-helpful">
 
-
-
-Read more about these and many other built-in pipes in the [pipes topics](api?type=pipe) of the
-[API Reference](api); filter for entries that include the word "pipe".
-
-Angular doesn't have a `FilterPipe` or an `OrderByPipe` for reasons explained in the [Appendix](guide/pipes#no-filter-pipe) of this page.
-
+* For a complete list of built-in pipes, see the [pipes API documentation](/api/common#pipes "Pipes API reference summary").
+* To learn more about using pipes for internationalization (i18n) efforts, see [formatting data based on locale](/guide/i18n#i18n-pipes "Formatting data based on locale").
 
 </div>
 
+You can also create pipes to encapsulate custom transformations and use your custom pipes in template expressions.
 
+## Prerequisites
 
+To use pipes you should have a basic understanding of the following:
 
-## Parameterizing a pipe
+* [Typescript](guide/glossary#typescript "Definition of Typescript") and HTML5 programming
+* [Templates](guide/glossary#template "Definition of a template") in HTML with CSS styles
+* [Components](guide/glossary#component "Definition of a component")
 
-A pipe can accept any number of optional parameters to fine-tune its output.
-To add parameters to a pipe, follow the pipe name with a colon ( : ) and then the parameter value
-(such as `currency:'EUR'`). If the pipe accepts multiple parameters, separate the values with colons (such as `slice:1:5`)
+## Using a pipe in a template
 
-Modify the birthday template to give the date pipe a format parameter.
-After formatting the hero's April 15th birthday, it renders as **<samp>04/15/88</samp>**:
+To apply a pipe, use the pipe operator (`|`) within a template expression as shown in the following code example, along with the *name* of the pipe, which is `date` for the built-in [`DatePipe`](api/common/DatePipe).
+The tabs in the example show the following:
 
+* `app.component.html` uses `date` in a separate template to display a birthday.
+* `hero-birthday1.component.ts` uses the same pipe as part of an in-line template in a component that also sets the birthday value.
 
-<code-example path="pipes/src/app/app.component.html" region="format-birthday" header="src/app/app.component.html"></code-example>
+<code-tabs>
+  <code-pane
+    header="src/app/app.component.html"
+    region="hero-birthday-template"
+    path="pipes/src/app/app.component.html">
+  </code-pane>
+  <code-pane
+    header="src/app/hero-birthday1.component.ts"
+    path="pipes/src/app/hero-birthday1.component.ts">
+  </code-pane>
+</code-tabs>
 
+The component's `birthday` value flows through the
+[pipe operator](guide/template-expression-operators#pipe) ( | ) to the [`date`](api/common/DatePipe)
+function.
 
+{@a parameterizing-a-pipe}
 
-The parameter value can be any valid template expression,
-(see the [Template expressions](guide/template-syntax#template-expressions) section of the
-[Template Syntax](guide/template-syntax) page)
-such as a string literal or a component property.
-In other words, you can control the format through a binding the same way you control the birthday value through a binding.
+## Transforming data with parameters and chained pipes
 
-Write a second component that *binds* the pipe's format parameter
-to the component's `format` property. Here's the template for that component:
+Use optional parameters to fine-tune a pipe's output.
+For example, you can use the [`CurrencyPipe`](api/common/CurrencyPipe "API reference") with a country code such as EUR as a parameter.
+The template expression `{{ amount | currency:'EUR' }}` transforms the `amount` to currency in euros.
+Follow the pipe name (`currency`) with a colon (`:`) and the parameter value (`'EUR'`).
 
+If the pipe accepts multiple parameters, separate the values with colons.
+For example, `{{ amount | currency:'EUR':'Euros '}}` adds the second parameter, the string literal `'Euros '`, to the output string. You can use any valid template expression as a parameter, such as a string literal or a component property.
 
-<code-example path="pipes/src/app/hero-birthday2.component.ts" region="template" header="src/app/hero-birthday2.component.ts (template)"></code-example>
+Some pipes require at least one parameter and allow more optional parameters, such as [`SlicePipe`](/api/common/SlicePipe "API reference for SlicePipe"). For example, `{{ slice:1:5 }}` creates a new array or string containing a subset of the elements starting with element `1` and ending with element `5`.
 
+### Example: Formatting a date
 
+The tabs in the following example demonstrates toggling between two different formats (`'shortDate'` and `'fullDate'`):
 
-You also added a button to the template and bound its click event to the component's `toggleFormat()` method.
-That method toggles the component's `format` property between a short form
+* The `app.component.html` template uses a format parameter for the [`DatePipe`](api/common/DatePipe) (named `date`) to show the date as **04/15/88**.
+* The `hero-birthday2.component.ts` component binds the pipe's format parameter to the component's `format` property in the `template` section, and adds a button for a click event bound to the component's `toggleFormat()` method.
+* The `hero-birthday2.component.ts` component's `toggleFormat()` method toggles the component's `format` property between a short form
 (`'shortDate'`) and a longer form (`'fullDate'`).
 
+<code-tabs>
+  <code-pane
+    header="src/app/app.component.html"
+    region="format-birthday"
+    path="pipes/src/app/app.component.html">
+  </code-pane>
+  <code-pane
+    header="src/app/hero-birthday2.component.ts (template)"
+    region="template"
+    path="pipes/src/app/hero-birthday2.component.ts">
+  </code-pane>
+  <code-pane
+    header="src/app/hero-birthday2.component.ts (class)"
+    region="class"
+    path="pipes/src/app/hero-birthday2.component.ts">
+  </code-pane>
+</code-tabs>
 
-<code-example path="pipes/src/app/hero-birthday2.component.ts" region="class" header="src/app/hero-birthday2.component.ts (class)"></code-example>
-
-
-
-As you click the button, the displayed date alternates between
-"**<samp>04/15/1988</samp>**" and
-"**<samp>Friday, April 15, 1988</samp>**".
+Clicking the **Toggle Format** button alternates the date format between **04/15/1988** and **Friday, April 15, 1988** as shown in Figure 1.
 
 <div class="lightbox">
   <img src='generated/images/guide/pipes/date-format-toggle-anim.gif' alt="Date Format Toggle">
 </div>
 
+**Figure 1.** Clicking the button toggles the date format
 
 <div class="alert is-helpful">
 
-
-
-Read more about the `DatePipe` format options in the [Date Pipe](api/common/DatePipe)
-API Reference page.
-
+For `date` pipe format options, see [DatePipe](api/common/DatePipe "DatePipe API Reference page").
 
 </div>
 
+### Example: Applying two formats by chaining pipes
 
+You can chain pipes so that the output of one pipe becomes the input to the next.
 
-## Chaining pipes
+In the following example, chained pipes first apply a format to a date value, then convert the formatted date to uppercase characters.
+The first tab for the `src/app/app.component.html` template chains `DatePipe` and `UpperCasePipe` to display the birthday as **APR 15, 1988**.
+The second tab for the `src/app/app.component.html` template passes the `fullDate` parameter to `date` before chaining to `uppercase`, which produces **FRIDAY, APRIL 15, 1988**.
 
-You can chain pipes together in potentially useful combinations.
-In the following example, to display the birthday in uppercase,
-the birthday is chained to the `DatePipe` and on to the `UpperCasePipe`.
-The birthday displays as **<samp>APR 15, 1988</samp>**.
+<code-tabs>
+  <code-pane
+    header="src/app/app.component.html (1)"
+    region="chained-birthday"
+    path="pipes/src/app/app.component.html">
+  </code-pane>
+  <code-pane
+    header="src/app/app.component.html (2)"
+    region="chained-parameter-birthday"
+    path="pipes/src/app/app.component.html">
+  </code-pane>
+</code-tabs>
 
+{@a Custom-pipes}
 
-<code-example path="pipes/src/app/app.component.html" region="chained-birthday" header="src/app/app.component.html"></code-example>
+## Creating pipes for custom data transformations
 
+Create custom pipes to encapsulate transformations that are not provided with the built-in pipes.
+You can then use your custom pipe in template expressions, the same way you use built-in pipes—to transform input values to output values for display.
 
+### Marking a class as a pipe
 
-This example&mdash;which displays **<samp>FRIDAY, APRIL 15, 1988</samp>**&mdash;chains
-the same pipes as above, but passes in a parameter to `date` as well.
+To mark a class as a pipe and supply configuration metadata, apply the [`@Pipe`](/api/core/Pipe "API reference for Pipe") [decorator](/guide/glossary#decorator--decoration "Definition for decorator") to the class.
+Use [UpperCamelCase](guide/glossary#case-types "Definition of case types") (the general convention for class names) for the pipe class name, and [camelCase](guide/glossary#case-types "Definition of case types") for the corresponding `name` string.
+Do not use hyphens in the `name`.
+For details and more examples, see [Pipe names](guide/styleguide#pipe-names "Pipe names in the Angular coding style guide").
 
+Use `name` in template expressions as you would for a built-in pipe.
 
-<code-example path="pipes/src/app/app.component.html" region="chained-parameter-birthday" header="src/app/app.component.html"></code-example>
+<div class="alert is-important">
 
-
-
-
-## Custom pipes
-
-You can write your own custom pipes.
-Here's a custom pipe named `ExponentialStrengthPipe` that can boost a hero's powers:
-
-
-<code-example path="pipes/src/app/exponential-strength.pipe.ts" header="src/app/exponential-strength.pipe.ts"></code-example>
-
-
-
-This pipe definition reveals the following key points:
-
-* A pipe is a class decorated with pipe metadata.
-* The pipe class implements the `PipeTransform` interface's `transform` method that
-accepts an input value followed by optional parameters and returns the transformed value.
-* There will be one additional argument to the `transform` method for each parameter passed to the pipe.
-Your pipe has one such parameter: the `exponent`.
-* To tell Angular that this is a pipe, you apply the
-`@Pipe` decorator, which you import from the core Angular library.
-* The `@Pipe` decorator allows you to define the
-   pipe name that you'll use within template expressions. It must be a valid JavaScript identifier.
-   Your pipe's name is `exponentialStrength`.
-
-
-<div class="alert is-helpful">
-
-
-
-## The *PipeTransform* interface
-
-The `transform` method is essential to a pipe.
-The `PipeTransform` *interface* defines that method and guides both tooling and the compiler.
-Technically, it's optional; Angular looks for and executes the `transform` method regardless.
+* Include your pipe in the `declarations` field of the `NgModule` metadata in order for it to be available to a template. See the `app.module.ts` file in the example app (<live-example></live-example>). For details, see [NgModules](guide/ngmodules "NgModules introduction").
+* Register your custom pipes. The [Angular CLI](cli "CLI Overview and Command Reference") [`ng generate pipe`](cli/generate#pipe "ng generate pipe in the CLI Command Reference") command registers the pipe automatically.
 
 </div>
 
-Now you need a component to demonstrate the pipe.
+### Using the PipeTransform interface
 
-<code-example path="pipes/src/app/power-booster.component.ts" header="src/app/power-booster.component.ts"></code-example>
+Implement the [`PipeTransform`](/api/core/PipeTransform "API reference for PipeTransform") interface in your custom pipe class to perform the transformation.
+
+Angular invokes the `transform` method with the value of a binding as the first argument, and any parameters as the second argument in list form, and returns the transformed value.
+
+### Example: Transforming a value exponentially
+
+In a game, you may want to implement a transformation that raises a value exponentially to increase a hero's power.
+For example, if the hero's score is 2, boosting the hero's power exponentially by 10 produces a score of 1024.
+You can use a custom pipe for this transformation.
+
+The following code example shows two component definitions:
+
+* The `exponential-strength.pipe.ts` component defines a custom pipe named `exponentialStrength` with the `transform` method that performs the transformation.
+It defines an argument to the `transform` method (`exponent`) for a parameter passed to the pipe.
+
+* The `power-booster.component.ts` component demonstrates how to use the pipe, specifying a value (`2`) and the exponent parameter (`10`).
+Figure 2 shows the output.
+
+<code-tabs>
+  <code-pane
+    header="src/app/exponential-strength.pipe.ts"
+    path="pipes/src/app/exponential-strength.pipe.ts">
+  </code-pane>
+  <code-pane
+    header="src/app/power-booster.component.ts"
+    path="pipes/src/app/power-booster.component.ts">
+  </code-pane>
+</code-tabs>
 
 <div class="lightbox">
   <img src='generated/images/guide/pipes/power-booster.png' alt="Power Booster">
 </div>
 
+**Figure 2.** Output from the `exponentialStrength` pipe
 
+<div class="alert is-helpful">
 
-Note the following:
-
-* You use your custom pipe the same way you use built-in pipes.
-* You must include your pipe in the `declarations` array of the `AppModule`
-* If you choose to inject your pipe into a class, you must provide it in the `providers` array of your `NgModule`.
-
-<div class="callout is-helpful">
-
-<header>
-  Remember the declarations array
-</header>
-
-
-You must register custom pipes.
-If you don't, Angular reports an error.
-The [Angular CLI's](cli) generator registers the pipe automatically.
-
+To examine the behavior the `exponentialStrength` pipe in the <live-example></live-example>, change the value and optional exponent in the template.
 
 </div>
 
+{@a change-detection}
 
+## Detecting changes with data binding in pipes
 
-To probe the behavior in the <live-example></live-example>,
-change the value and optional exponent in the template.
-
-## Power Boost Calculator
-
-It's not much fun updating the template to test the custom pipe.
-Upgrade the example to a "Power Boost Calculator" that combines
-your pipe and two-way data binding with `ngModel`.
+You use [data binding](/guide/glossary#data-binding "Definition of data binding") with a  pipe to display values and respond to user actions.
+If the data is a primitive input value, such as `String` or `Number`, or an object reference as input, such as `Date` or `Array`, Angular executes the pipe whenever it detects a change for the input value or reference.
 
+For example, you could change the previous custom pipe example to use two-way data binding with `ngModel` to input the amount and boost factor, as shown in the following code example.
 
 <code-example path="pipes/src/app/power-boost-calculator.component.ts" header="src/app/power-boost-calculator.component.ts">
 
 </code-example>
 
-
+The `exponentialStrength` pipe executes every time the user changes the "normal power" value or the "boost factor", as shown in Figure 3.
 
 <div class="lightbox">
   <img src='generated/images/guide/pipes/power-boost-calculator-anim.gif' alt="Power Boost Calculator">
 </div>
 
+**Figure 3.** Changing the amount and boost factor for the `exponentialStrength` pipe
 
+Angular detects each change and immediately runs the pipe.
+This is fine for primitive input values.
+However, if you change something *inside* a composite object (such as the month of a date, an element of an array, or an object property), you need to understand how change detection works, and how to use an `impure` pipe.
 
+### How change detection works
 
-{@a change-detection}
+Angular looks for changes to data-bound values in a [change detection](guide/glossary#change-detection "Definition of change detection") process that runs after every DOM event: every keystroke, mouse move, timer tick, and server response.
+The following example, which doesn't use a pipe, demonstrates how Angular uses its default change detection strategy to monitor and update its display of every hero in the `heroes` array.
+The example tabs show the following:
 
+* In the `flying-heroes.component.html (v1)` template, the `*ngFor` repeater displays the hero names.
+* Its companion component class `flying-heroes.component.ts (v1)` provides heroes, adds heroes into the array, and resets the array.
 
-## Pipes and change detection
+<code-tabs>
+  <code-pane
+    header="src/app/flying-heroes.component.html (v1)"
+    region="template-1"
+    path="pipes/src/app/flying-heroes.component.html">
+  </code-pane>
+  <code-pane
+    header="src/app/flying-heroes.component.ts (v1)"
+    region="v1"
+    path="pipes/src/app/flying-heroes.component.ts">
+  </code-pane>
+</code-tabs>
 
-Angular looks for changes to data-bound values through a *change detection* process that runs after every DOM event:
-every keystroke, mouse move, timer tick, and server response. This could be expensive.
-Angular strives to lower the cost whenever possible and appropriate.
+Angular updates the display every time the user adds a hero.
+If the user clicks the **Reset** button, Angular replaces `heroes` with a new array of the original heroes and updates the display.
+If you add the ability to remove or change a hero, Angular would detect those changes and update the display as well.
 
-Angular picks a simpler, faster change detection algorithm when you use a pipe.
+However, executing a pipe to update the display with every change would slow down your app's performance.
+So Angular uses a faster change-detection algorithm for executing a pipe, as described in the next section.
 
-<h3 class="no-toc">No pipe</h3>
+{@a pure-and-impure-pipes}
 
-In the next example, the component uses the default, aggressive change detection strategy to monitor and update
-its display of every hero in the `heroes` array. Here's the template:
+### Detecting pure changes to primitives and object references
 
+By default, pipes are defined as *pure* so that Angular executes the pipe only when it detects a *pure change* to the input value.
+A pure change is either a change to a primitive input value (such as `String`, `Number`, `Boolean`, or `Symbol`), or a changed object reference (such as `Date`, `Array`, `Function`, or `Object`).
 
-<code-example path="pipes/src/app/flying-heroes.component.html" region="template-1" header="src/app/flying-heroes.component.html (v1)"></code-example>
+{@a pure-pipe-pure-fn}
 
+A pure pipe must use a pure function, which is one that processes inputs and returns values without side effects.
+In other words, given the same input, a pure function should always return the same output.
 
+With a pure pipe, Angular ignores changes within composite objects, such as a newly added element of an existing array, because checking a primitive value or object reference is much faster than performing a deep check for differences within objects.
+Angular can quickly determine if it can skip executing the pipe and updating the view.
 
-The companion component class provides heroes, adds heroes into the array, and can reset the array.
+However, a pure pipe with an array as input may not work the way you want.
+To demonstrate this issue, change the previous example to filter the list of heroes to just those heroes who can fly.
+Use the `FlyingHeroesPipe` in the `*ngFor` repeater as shown in the following code.
+The tabs for the example show the following:
 
-<code-example path="pipes/src/app/flying-heroes.component.ts" region="v1" header="src/app/flying-heroes.component.ts (v1)"></code-example>
+* The template (`flying-heroes.component.html (flyers)`) with the new pipe.
+* The `FlyingHeroesPipe` custom pipe implementation (`flying-heroes.pipe.ts`).
 
+<code-tabs>
+  <code-pane
+    header="src/app/flying-heroes.component.html (flyers)"
+    region="template-flying-heroes"
+    path="pipes/src/app/flying-heroes.component.html">
+  </code-pane>
+  <code-pane
+    header="src/app/flying-heroes.pipe.ts"
+    region="pure"
+    path="pipes/src/app/flying-heroes.pipe.ts">
+  </code-pane>
+</code-tabs>
 
-
-You can add heroes and Angular updates the display when you do.
-If you click the `reset` button, Angular replaces `heroes` with a new array of the original heroes and updates the display.
-If you added the ability to remove or change a hero, Angular would detect those changes and update the display as well.
-
-<h3 class="no-toc"><i>FlyingHeroesPipe</i></h3>
-
-Add a `FlyingHeroesPipe` to the `*ngFor` repeater that filters the list of heroes to just those heroes who can fly.
-
-<code-example path="pipes/src/app/flying-heroes.component.html" region="template-flying-heroes" header="src/app/flying-heroes.component.html (flyers)"></code-example>
-
-
-
-Here's the `FlyingHeroesPipe` implementation, which follows the pattern for custom pipes described earlier.
-
-<code-example path="pipes/src/app/flying-heroes.pipe.ts" region="pure" header="src/app/flying-heroes.pipe.ts"></code-example>
-
-
-
-Notice the odd behavior in the <live-example></live-example>:
-when you add flying heroes, none of them are displayed under "Heroes who fly."
-
-Although you're not getting the behavior you want, Angular isn't broken.
-It's just using a different change-detection algorithm that ignores changes to the list or any of its items.
-
-Notice how a hero is added:
+The app now shows unexpected behavior: When the user adds flying heroes, none of them appear under "Heroes who fly."
+This happens because the code that adds a hero does so by pushing it onto the `heroes` array:
 
 <code-example path="pipes/src/app/flying-heroes.component.ts" region="push" header="src/app/flying-heroes.component.ts"></code-example>
 
+The change detector ignores changes to elements of an array, so the pipe doesn't run.
 
+The reason Angular ignores the changed array element is that the *reference* to the array hasn't changed.
+Since the array is the same, Angular does not update the display.
 
-You add the hero into the `heroes` array. The reference to the array hasn't changed.
-It's the same array. That's all Angular cares about. From its perspective, *same array, no change, no display update*.
-
-To fix that, create an array with the new hero appended and assign that to `heroes`.
-This time Angular detects that the array reference has changed.
-It executes the pipe and updates the display with the new array, which includes the new flying hero.
-
-If you *mutate* the array, no pipe is invoked and the display isn't updated;
-if you *replace* the array, the pipe executes and the display is updated.
-The Flying Heroes application extends the
-code with checkbox switches and additional displays to help you experience these effects.
+One way to get the behavior you want is to change the object reference itself.
+You can replace the array with a new array containing the newly changed elements, and then input the new array to the pipe.
+In the above example, you can create an array with the new hero appended, and assign that to `heroes`. Angular detects the change in the array reference and executes the pipe.
 
+To summarize, if you mutate the input array, the pure pipe doesn't execute.
+If you *replace* the input array, the pipe executes and the display is updated, as shown in Figure 4.
 
 <div class="lightbox">
   <img src='generated/images/guide/pipes/flying-heroes-anim.gif' alt="Flying Heroes">
 </div>
 
+**Figure 4.** The `flyingHeroes` pipe filtering the display to flying heroes
 
+The above example demonstrates changing a component's code to accommodate a pipe.
 
-Replacing the array is an efficient way to signal Angular to update the display.
-When do you replace the array? When the data changes.
-That's an easy rule to follow in *this* example
-where the only way to change the data is by adding a hero.
-
-More often, you don't know when the data has changed,
-especially in applications that mutate data in many ways,
-perhaps in application locations far away.
-A component in such an application usually can't know about those changes.
-Moreover, it's unwise to distort the component design to accommodate a pipe.
-Strive to keep the component class independent of the HTML.
-The component should be unaware of pipes.
-
-For filtering flying heroes, consider an *impure pipe*.
-
-
-
-## Pure and impure pipes
-
-There are two categories of pipes: *pure* and *impure*.
-Pipes are pure by default. Every pipe you've seen so far has been pure.
-You make a pipe impure by setting its pure flag to false. You could make the `FlyingHeroesPipe`
-impure like this:
-
-
-<code-example path="pipes/src/app/flying-heroes.pipe.ts" region="pipe-decorator" header="src/app/flying-heroes.pipe.ts"></code-example>
-
-
-
-Before doing that, understand the difference between pure and impure, starting with a pure pipe.
-
-<h3 class="no-toc">Pure pipes</h3>
-
-Angular executes a *pure pipe* only when it detects a *pure change* to the input value.
-A pure change is either a change to a primitive input value (`String`, `Number`, `Boolean`, `Symbol`)
-or a changed object reference (`Date`, `Array`, `Function`, `Object`).
-
-Angular ignores changes within (composite) objects.
-It won't call a pure pipe if you change an input month, add to an input array, or update an input object property.
-
-This may seem restrictive but it's also fast.
-An object reference check is fast&mdash;much faster than a deep check for
-differences&mdash;so Angular can quickly determine if it can skip both the
-pipe execution and a view update.
-
-For this reason, a pure pipe is preferable when you can live with the change detection strategy.
-When you can't, you *can* use the impure pipe.
-
-
-<div class="alert is-helpful">
-
-
-
-Or you might not use a pipe at all.
-It may be better to pursue the pipe's purpose with a property of the component,
-a point that's discussed later in this page.
-
-
-</div>
-
-
-
-<h3 class="no-toc">Impure pipes</h3>
-
-Angular executes an *impure pipe*  during every component change detection cycle.
-An impure pipe is called often, as often as every keystroke or mouse-move.
-
-With that concern in mind, implement an impure pipe with great care.
-An expensive, long-running pipe could destroy the user experience.
-
+To keep your component simpler and independent of HTML templates that use pipes, you can, as an alternative, use an *impure* pipe to detect changes within composite objects such as arrays, as described in the next section.
 
 {@a impure-flying-heroes}
 
+### Detecting impure changes within composite objects
 
-<h3 class="no-toc">An impure <i>FlyingHeroesPipe</i></h3>
+To execute a custom pipe after a change *within* a composite object, such as a change to an element of an array, you need to define your pipe as `impure` to detect impure changes.
+Angular executes an impure pipe every time it detects a change with every keystroke or mouse movement.
 
-A flip of the switch turns the `FlyingHeroesPipe` into a `FlyingHeroesImpurePipe`.
-The complete implementation is as follows:
+<div class="alert is-important">
+
+While an impure pipe can be useful, be careful using one. A long-running impure pipe could dramatically slow down your app.
+
+</div>
+
+Make a pipe impure by setting its `pure` flag to `false`:
+
+<code-example path="pipes/src/app/flying-heroes.pipe.ts" region="pipe-decorator" header="src/app/flying-heroes.pipe.ts"></code-example>
+
+The following code shows the complete implementation of `FlyingHeroesImpurePipe`, which extends `FlyingHeroesPipe` to inherit its characteristics.
+The example shows that you don't have to change anything else—the only difference is setting the `pure` flag as `false` in the pipe metadata.
 
 <code-tabs>
-
-  <code-pane header="FlyingHeroesImpurePipe" path="pipes/src/app/flying-heroes.pipe.ts" region="impure">
-
+  <code-pane
+    header="src/app/flying-heroes.pipe.ts (FlyingHeroesImpurePipe)"
+    region="impure"
+    path="pipes/src/app/flying-heroes.pipe.ts">
   </code-pane>
-
-  <code-pane header="FlyingHeroesPipe" path="pipes/src/app/flying-heroes.pipe.ts" region="pure">
-
+  <code-pane
+    header="src/app/flying-heroes.pipe.ts (FlyingHeroesPipe)"
+    region="pure"
+    path="pipes/src/app/flying-heroes.pipe.ts">
   </code-pane>
-
 </code-tabs>
 
-
-
-You inherit from `FlyingHeroesPipe` to prove the point that nothing changed internally.
-The only difference is the `pure` flag in the pipe metadata.
-
-This is a good candidate for an impure pipe because the `transform` function is trivial and fast.
-
+`FlyingHeroesImpurePipe` is a good candidate for an impure pipe because the `transform` function is trivial and fast:
 
 <code-example path="pipes/src/app/flying-heroes.pipe.ts" header="src/app/flying-heroes.pipe.ts (filter)" region="filter"></code-example>
 
-
-
 You can derive a `FlyingHeroesImpureComponent` from `FlyingHeroesComponent`.
-
+As shown in the code below, only the pipe in the template changes.
 
 <code-example path="pipes/src/app/flying-heroes-impure.component.html" header="src/app/flying-heroes-impure.component.html (excerpt)" region="template-flying-heroes"></code-example>
 
+<div class="alert is-helpful">
 
+  To confirm that the display updates as the user adds heroes, see the <live-example></live-example>.
 
-The only substantive change is the pipe in the template.
-You can confirm in the <live-example></live-example> that the _flying heroes_
-display updates as you add heroes, even when you mutate the `heroes` array.
-
+</div>
 
 {@a async-pipe}
-<h3 class="no-toc">The impure <i>AsyncPipe</i></h3>
 
+## Unwrapping data from an observable
 
-The Angular `AsyncPipe` is an interesting example of an impure pipe.
-The `AsyncPipe` accepts a `Promise` or `Observable` as input
-and subscribes to the input automatically, eventually returning the emitted values.
+[Observables](/guide/glossary#observable "Definition of observable") let you pass messages between parts of your application.
+Observables are recommended for event handling, asynchronous programming, and handling multiple values.
+Observables can deliver single or multiple values of any type, either synchronously (as a function delivers a value to its caller) or asynchronously on a schedule.
 
-The `AsyncPipe` is also stateful.
-The pipe maintains a subscription to the input `Observable` and
-keeps delivering values from that `Observable` as they arrive.
+<div class="alert is-helpful">
 
-This next example binds an `Observable` of message strings
+For details and examples of observables, see the [Observables Overview](/guide/observables#using-observables-to-pass-values "Using observables to pass values"").
+
+</div>
+
+Use the built-in [`AsyncPipe`](/api/common/AsyncPipe "API description of AsyncPipe") to accept an observable as input and subscribe to the input automatically.
+Without this pipe, your component code would have to subscribe to the observable to consume its values, extract the resolved values, expose them for binding, and unsubscribe when the observable is destroyed in order to prevent memory leaks. `AsyncPipe` is an impure pipe that saves boilerplate code in your component to maintain the subscription and keep delivering values from that observable as they arrive.
+
+The following code example binds an observable of message strings
 (`message$`) to a view with the `async` pipe.
 
-
 <code-example path="pipes/src/app/hero-async-message.component.ts" header="src/app/hero-async-message.component.ts">
 
 </code-example>
 
+{@a no-filter-pipe}
 
+## Caching HTTP requests
 
-The Async pipe saves boilerplate in the component code.
-The component doesn't have to subscribe to the async data source,
-extract the resolved values and expose them for binding,
-and have to unsubscribe when it's destroyed
-(a potent source of memory leaks).
+To [communicate with backend services using HTTP](/guide/http "Communicating with backend services using HTTP"), the `HttpClient` service uses observables and offers the `HTTPClient.get()` method to fetch data from a server.
+The aynchronous method sends an HTTP request, and returns an observable that emits the requested data for the response.
 
-<h3 class="no-toc">An impure caching pipe</h3>
+As shown in the previous section, you can use the impure `AsyncPipe` to accept an observable as input and subscribe to the input automatically.
+You can also create an impure pipe to make and cache an HTTP request.
 
-Write one more impure pipe, a pipe that makes an HTTP request.
+Impure pipes are called whenever change detection runs for a component, which could be every few milliseconds for `CheckAlways`.
+To avoid performance problems, call the server only when the requested URL changes, as shown in the following example, and use the pipe to cache the server response.
+The tabs show the following:
 
-Remember that impure pipes are called every few milliseconds.
-If you're not careful, this pipe will punish the server with requests.
+* The `fetch` pipe (`fetch-json.pipe.ts`).
+* A harness component (`hero-list.component.ts`) for demonstrating the request, using a template that defines two bindings to the pipe requesting the heroes from the `heroes.json` file. The second binding chains the `fetch` pipe with the built-in `JsonPipe` to display the same hero data in JSON format.
 
-In the following code, the pipe only calls the server when the requested URL changes and it caches the server response.
-The code uses the [Angular http](guide/http) client to retrieve data:
+<code-tabs>
+  <code-pane
+    header="src/app/fetch-json.pipe.ts"
+    path="pipes/src/app/fetch-json.pipe.ts">
+  </code-pane>
+  <code-pane
+    header="src/app/hero-list.component.ts"
+    path="pipes/src/app/hero-list.component.ts">
+  </code-pane>
+</code-tabs>
 
+In the above example, a breakpoint on the pipe's request for data shows the following:
 
-<code-example path="pipes/src/app/fetch-json.pipe.ts" header="src/app/fetch-json.pipe.ts">
-
-</code-example>
-
-
-
-Now demonstrate it in a harness component whose template defines two bindings to this pipe,
-both requesting the heroes from the `heroes.json` file.
-
-
-<code-example path="pipes/src/app/hero-list.component.ts" header="src/app/hero-list.component.ts">
-
-</code-example>
-
-
-
-The component renders as the following:
+* Each binding gets its own pipe instance.
+* Each pipe instance caches its own URL and data and calls the server only once.
 
+The `fetch` and `fetch-json` pipes display the heroes as shown in Figure 5.
 
 <div class="lightbox">
   <img src='generated/images/guide/pipes/hero-list.png' alt="Hero List">
 </div>
 
+**Figure 5.** The `fetch` and `fetch-json` pipes displaying the heroes
 
+<div class="alert is-helpful">
 
-A breakpoint on the pipe's request for data shows the following:
-
-* Each binding gets its own pipe instance.
-* Each pipe instance caches its own URL and data.
-* Each pipe instance only calls the server once.
-
-<h3 class="no-toc"><i>JsonPipe</i></h3>
-
-In the previous code sample, the second `fetch` pipe binding demonstrates more pipe chaining.
-It displays the same hero data in JSON format by chaining through to the built-in `JsonPipe`.
-
-
-<div class="callout is-helpful">
-
-
-
-<header>
-  Debugging with the json pipe
-</header>
-
-
-
-The [JsonPipe](api/common/JsonPipe)
-provides an easy way to diagnose a mysteriously failing data binding or
-inspect an object for future binding.
-
+The built-in [JsonPipe](api/common/JsonPipe "API description for JsonPipe") provides a way to diagnose a mysteriously failing data binding or to inspect an object for future binding.
 
 </div>
-
-
-
-{@a pure-pipe-pure-fn}
-
-
-<h3 class="no-toc">Pure pipes and pure functions</h3>
-
-A pure pipe uses pure functions.
-Pure functions process inputs and return values without detectable side effects.
-Given the same input, they should always return the same output.
-
-The pipes discussed earlier in this page are implemented with pure functions.
-The built-in `DatePipe` is a pure pipe with a pure function implementation.
-So are the `ExponentialStrengthPipe` and `FlyingHeroesPipe`.
-A few steps back, you reviewed the `FlyingHeroesImpurePipe`&mdash;an impure pipe with a pure function.
-
-But always implement a *pure pipe* with a *pure function*.
-Otherwise, you'll see many console errors regarding expressions that changed after they were checked.
-
-
-
-## Next steps
-
-Pipes are a great way to encapsulate and share common display-value
-transformations. Use them like styles, dropping them
-into your template's expressions to enrich the appeal and usability
-of your views.
-
-Explore Angular's inventory of built-in pipes in the [API Reference](api?type=pipe).
-Try writing a custom pipe and perhaps contributing it to the community.
-
-
-{@a no-filter-pipe}
-
-
-
-## Appendix: No *FilterPipe* or *OrderByPipe*
-
-Angular doesn't provide pipes for filtering or sorting lists.
-Developers familiar with AngularJS know these as `filter` and `orderBy`.
-There are no equivalents in Angular.
-
-This isn't an oversight. Angular doesn't offer such pipes because
-they perform poorly and prevent aggressive minification.
-Both `filter` and `orderBy` require parameters that reference object properties.
-Earlier in this page, you learned that such pipes must be [impure](guide/pipes#pure-and-impure-pipes) and that
-Angular calls impure pipes in almost every change-detection cycle.
-
-Filtering and especially sorting are expensive operations.
-The user experience can degrade severely for even moderate-sized lists when Angular calls these pipe methods many times per second.
-`filter` and `orderBy` have often been abused in AngularJS apps, leading to complaints that Angular itself is slow.
-That charge is fair in the indirect sense that AngularJS prepared this performance trap
-by offering `filter` and `orderBy` in the first place.
-
-The minification hazard is also compelling, if less obvious. Imagine a sorting pipe applied to a list of heroes.
-The list might be sorted by hero `name` and `planet` of origin properties in the following way:
-
-<code-example language="html">
-  &lt;!-- NOT REAL CODE! -->
-  &lt;div *ngFor="let hero of heroes | orderBy:'name,planet'">&lt;/div>
-</code-example>
-
-
-
-You identify the sort fields by text strings, expecting the pipe to reference a property value by indexing
-(such as `hero['name']`).
-Unfortunately, aggressive minification manipulates the `Hero` property names so that `Hero.name` and `Hero.planet`
-become something like `Hero.a` and `Hero.b`. Clearly `hero['name']` doesn't work.
-
-While some may not care to minify this aggressively,
-the Angular product shouldn't prevent anyone from minifying aggressively.
-Therefore, the Angular team decided that everything Angular provides will minify safely.
-
-The Angular team and many experienced Angular developers strongly recommend moving
-filtering and sorting logic into the component itself.
-The component can expose a `filteredHeroes` or `sortedHeroes` property and take control
-over when and how often to execute the supporting logic.
-Any capabilities that you would have put in a pipe and shared across the app can be
-written in a filtering/sorting service and injected into the component.
-
-If these performance and minification considerations don't apply to you, you can always create your own such pipes
-(similar to the [FlyingHeroesPipe](guide/pipes#impure-flying-heroes)) or find them in the community.

aio/content/guide/property-binding.md

@@ -0,0 +1,228 @@
+
+# Property binding `[property]`
+
+Use property binding to _set_ properties of target elements or
+directive `@Input()` decorators.
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+## One-way in
+
+Property binding flows a value in one direction,
+from a component's property into a target element property.
+
+You can't use property
+binding to read or pull values out of target elements. Similarly, you cannot use
+property binding to call a method on the target element.
+If the element raises events, you can listen to them with an [event binding](guide/event-binding).
+
+If you must read a target element property or call one of its methods,
+see the API reference for [ViewChild](api/core/ViewChild) and
+[ContentChild](api/core/ContentChild).
+
+## Examples
+
+The most common property binding sets an element property to a component
+property value. An example is
+binding the `src` property of an image element to a component's `itemImageUrl` property:
+
+<code-example path="property-binding/src/app/app.component.html" region="property-binding" header="src/app/app.component.html"></code-example>
+
+Here's an example of binding to the `colSpan` property. Notice that it's not `colspan`,
+which is the attribute, spelled with a lowercase `s`.
+
+<code-example path="property-binding/src/app/app.component.html" region="colSpan" header="src/app/app.component.html"></code-example>
+
+For more details, see the [MDN HTMLTableCellElement](https://developer.mozilla.org/en-US/docs/Web/API/HTMLTableCellElement) documentation.
+
+For more information about `colSpan` and `colspan`, see the [Attribute binding](guide/attribute-binding#colspan) guide.
+
+Another example is disabling a button when the component says that it `isUnchanged`:
+
+<code-example path="property-binding/src/app/app.component.html" region="disabled-button" header="src/app/app.component.html"></code-example>
+
+Another is setting a property of a directive:
+
+<code-example path="property-binding/src/app/app.component.html" region="class-binding" header="src/app/app.component.html"></code-example>
+
+Yet another is setting the model property of a custom component&mdash;a great way
+for parent and child components to communicate:
+
+<code-example path="property-binding/src/app/app.component.html" region="model-property-binding" header="src/app/app.component.html"></code-example>
+
+## Binding targets
+
+An element property between enclosing square brackets identifies the target property.
+The target property in the following code is the image element's `src` property.
+
+<code-example path="property-binding/src/app/app.component.html" region="property-binding" header="src/app/app.component.html"></code-example>
+
+There's also the `bind-` prefix alternative:
+
+<code-example path="property-binding/src/app/app.component.html" region="bind-prefix" header="src/app/app.component.html"></code-example>
+
+
+In most cases, the target name is the name of a property, even
+when it appears to be the name of an attribute.
+So in this case, `src` is the name of the `<img>` element property.
+
+Element properties may be the more common targets,
+but Angular looks first to see if the name is a property of a known directive,
+as it is in the following example:
+
+<code-example path="property-binding/src/app/app.component.html" region="class-binding" header="src/app/app.component.html"></code-example>
+
+Technically, Angular is matching the name to a directive `@Input()`,
+one of the property names listed in the directive's `inputs` array
+or a property decorated with `@Input()`.
+Such inputs map to the directive's own properties.
+
+If the name fails to match a property of a known directive or element, Angular reports an “unknown directive” error.
+
+<div class="alert is-helpful">
+
+Though the target name is usually the name of a property,
+there is an automatic attribute-to-property mapping in Angular for
+several common attributes. These include `class`/`className`, `innerHtml`/`innerHTML`, and
+`tabindex`/`tabIndex`.
+
+</div>
+
+
+## Avoid side effects
+
+Evaluation of a template expression should have no visible side effects.
+The expression language itself, or the way you write template expressions,
+helps to a certain extent;
+you can't assign a value to anything in a property binding expression
+nor use the increment and decrement operators.
+
+For example, you could have an expression that invoked a property or method that had
+side effects. The expression could call something like `getFoo()` where only you
+know what `getFoo()` does. If `getFoo()` changes something
+and you happen to be binding to that something,
+Angular may or may not display the changed value. Angular may detect the
+change and throw a warning error.
+As a best practice, stick to properties and to methods that return
+values and avoid side effects.
+
+## Return the proper type
+
+The template expression should evaluate to the type of value
+that the target property expects.
+Return a string if the target property expects a string, a number if it
+expects a number, an object if it expects an object, and so on.
+
+In the following example, the `childItem` property of the `ItemDetailComponent` expects a string, which is exactly what you're sending in the property binding:
+
+<code-example path="property-binding/src/app/app.component.html" region="model-property-binding" header="src/app/app.component.html"></code-example>
+
+You can confirm this by looking in the `ItemDetailComponent` where the `@Input` type is set to a string:
+<code-example path="property-binding/src/app/item-detail/item-detail.component.ts" region="input-type" header="src/app/item-detail/item-detail.component.ts (setting the @Input() type)"></code-example>
+
+As you can see here, the `parentItem` in `AppComponent` is a string, which the `ItemDetailComponent` expects:
+<code-example path="property-binding/src/app/app.component.ts" region="parent-data-type" header="src/app/app.component.ts"></code-example>
+
+### Passing in an object
+
+The previous simple example showed passing in a string. To pass in an object,
+the syntax and thinking are the same.
+
+In this scenario, `ItemListComponent` is nested within `AppComponent` and the `items` property expects an array of objects.
+
+<code-example path="property-binding/src/app/app.component.html" region="pass-object" header="src/app/app.component.html"></code-example>
+
+The `items` property is declared in the `ItemListComponent` with a type of `Item` and decorated with `@Input()`:
+
+<code-example path="property-binding/src/app/item-list/item-list.component.ts" region="item-input" header="src/app/item-list.component.ts"></code-example>
+
+In this sample app, an `Item` is an object that has two properties; an `id` and a `name`.
+
+<code-example path="property-binding/src/app/item.ts" region="item-class" header="src/app/item.ts"></code-example>
+
+While a list of items exists in another file, `mock-items.ts`, you can
+specify a different item in `app.component.ts` so that the new item will render:
+
+<code-example path="property-binding/src/app/app.component.ts" region="pass-object" header="src/app.component.ts"></code-example>
+
+You just have to make sure, in this case, that you're supplying an array of objects because that's the type of `Item` and is what the nested component, `ItemListComponent`, expects.
+
+In this example, `AppComponent` specifies a different `item` object
+(`currentItems`) and passes it to the nested `ItemListComponent`. `ItemListComponent` was able to use `currentItems` because it matches what an `Item` object is according to `item.ts`. The `item.ts` file is where
+`ItemListComponent` gets its definition of an `item`.
+
+## Remember the brackets
+
+The brackets, `[]`, tell Angular to evaluate the template expression.
+If you omit the brackets, Angular treats the string as a constant
+and *initializes the target property* with that string:
+
+<code-example path="property-binding/src/app/app.component.html" region="no-evaluation" header="src/app.component.html"></code-example>
+
+
+Omitting the brackets will render the string
+`parentItem`, not the value of `parentItem`.
+
+## One-time string initialization
+
+You *should* omit the brackets when all of the following are true:
+
+* The target property accepts a string value.
+* The string is a fixed value that you can put directly into the template.
+* This initial value never changes.
+
+You routinely initialize attributes this way in standard HTML, and it works
+just as well for directive and component property initialization.
+The following example initializes the `prefix` property of the `StringInitComponent` to a fixed string,
+not a template expression. Angular sets it and forgets about it.
+
+<code-example path="property-binding/src/app/app.component.html" region="string-init" header="src/app/app.component.html"></code-example>
+
+The `[item]` binding, on the other hand, remains a live binding to the component's `currentItems` property.
+
+## Property binding vs. interpolation
+
+You often have a choice between interpolation and property binding.
+The following binding pairs do the same thing:
+
+<code-example path="property-binding/src/app/app.component.html" region="property-binding-interpolation" header="src/app/app.component.html"></code-example>
+
+Interpolation is a convenient alternative to property binding in
+many cases. When rendering data values as strings, there is no
+technical reason to prefer one form to the other, though readability
+tends to favor interpolation. However, *when setting an element
+property to a non-string data value, you must use property binding*.
+
+## Content security
+
+Imagine the following malicious content.
+
+<code-example path="property-binding/src/app/app.component.ts" region="malicious-content" header="src/app/app.component.ts"></code-example>
+
+In the component template, the content might be used with interpolation:
+
+<code-example path="property-binding/src/app/app.component.html" region="malicious-interpolated" header="src/app/app.component.html"></code-example>
+
+Fortunately, Angular data binding is on alert for dangerous HTML. In the above case,
+the HTML displays as is, and the Javascript does not execute. Angular **does not**
+allow HTML with script tags to leak into the browser, neither with interpolation
+nor property binding.
+
+In the following example, however, Angular [sanitizes](guide/security#sanitization-and-security-contexts)
+the values before displaying them.
+
+<code-example path="property-binding/src/app/app.component.html" region="malicious-content" header="src/app/app.component.html"></code-example>
+
+Interpolation handles the `<script>` tags differently than
+property binding but both approaches render the
+content harmlessly. The following is the browser output
+of the `evilTitle` examples.
+
+<code-example language="bash">
+"Template <script>alert("evil never sleeps")</script> Syntax" is the interpolated evil title.
+"Template alert("evil never sleeps")Syntax" is the property bound evil title.
+</code-example>

aio/content/guide/providers.md

@@ -52,6 +52,14 @@ Any component created within a lazy loaded module’s context, such as by router
 
 Though you can provide services by lazy loading modules, not all services can be lazy loaded. For instance, some modules only work in the root module, such as the Router. The Router works with the global location object in the browser.
 
+As of Angular version 9, you can provide a new instance of a service with each lazy loaded module. The following code adds this functionality to `UserService`.
+
+<code-example path="providers/src/app/user.service.2.ts"  header="src/app/user.service.ts"></code-example>
+
+With `providedIn: 'any'`, all eagerly loaded modules share a singleton instance; however, lazy loaded modules each get their own unique instance, as shown in the following diagram.
+
+<img src="generated/images/guide/providers/any-provider.svg" alt="any-provider-scope" class="left">
+
 
 ## Limiting provider scope with components
 

aio/content/guide/releases.md

@@ -101,6 +101,7 @@ The following table provides the status for Angular versions under support.
 
 Version | Status | Released     | Active Ends  | LTS Ends
 ------- | ------ | ------------ | ------------ | ------------
+^10.0.0 | Active | Jun 24, 2020 | Dec 24, 2020 | Dec 24, 2021
 ^9.0.0  | Active | Feb 06, 2020 | Aug 06, 2020 | Aug 06, 2021
 ^8.0.0  | LTS    | May 28, 2019 | Nov 28, 2019 | Nov 28, 2020
 

aio/content/guide/route-animations.md

@@ -111,7 +111,7 @@ Let's assume that we are routing from the *Home => About*.
 
 The animation code does the following after styling the views:
 
-* `query(':enter style({ left: '-100%'})` matches the view that is added and hides the newly added view by positioning it to the far left.
+* `query(':enter', style({ left: '-100%' }))` matches the view that is added and hides the newly added view by positioning it to the far left.
 * Calls `animateChild()` on the view that is leaving, to run its child animations.
 * Uses `group()` function to make the inner animations run in parallel.
 * Within the `group()` function:

aio/content/guide/router-tutorial.md

@@ -4,7 +4,7 @@ This tutorial describes how you can build a single-page application, SPA that us
 
 
 In an SPA, all of your application's functions exist in a single HTML page.
-As users access your application's features, the browser needs to render only the parts that matter to the user, instead of loading a new page. This pattern can significantly improve your application's user exprience.
+As users access your application's features, the browser needs to render only the parts that matter to the user, instead of loading a new page. This pattern can significantly improve your application's user experience.
 
 To define how users navigate through your application, you use routes. You can add routes to define how users navigate from one part of your application to another.
 You can also configure routes to guard against unexpected or unauthorized behavior.
@@ -105,7 +105,7 @@ In this section, you'll define two routes:
 * The route `/crisis-center` opens the `crisis-center` component.
 * The route `/heroes-list` opens the `heroes-list` component.
 
-A route definition is a JavaScript object. Each route typically has two propteries. The first property, `path`, is a string
+A route definition is a JavaScript object. Each route typically has two properties. The first property, `path`, is a string
 that specifies the URL path for the route. The second property, `component`, is a string that specifies
 what component your application should display for that path.
 
@@ -220,7 +220,7 @@ Now when you open your application, it displays the `heroes-list` component by d
 ## Adding a 404 page
 
 It is possible for a user to try to access a route that you have not defined. To account for
-this behavior, a best practice is to display a 404 page. In this section, you'll create a 404 page and
+this behavior, the best practice is to display a 404 page. In this section, you'll create a 404 page and
 update your route configuration to show that page for any unspecified routes.
 
 1. From the terminal, create a new component, `PageNotFound`.

aio/content/guide/schematics-for-libraries.md

@@ -1,7 +1,7 @@
 # Schematics for libraries
 
 When you create an Angular library, you can provide and package it with schematics that integrate it with the Angular CLI.
-With your schematics, your users can use  `ng add` to install an initial version of your library,
+With your schematics, your users can use `ng add` to install an initial version of your library,
 `ng generate` to create artifacts defined in your library, and `ng update` to adjust their project for a new version of your library that introduces breaking changes.
 
 All three types of schematics can be part of a collection that you package with your library.
@@ -57,6 +57,20 @@ The task uses the user's preferred package manager to add the library to the pro
 In this example, the function receives the current `Tree` and returns it without any modifications.
 If you need to, you can do additional setup when your package is installed, such as generating files, updating configuration, or any other initial setup your library requires.
 
+### Define dependency type
+
+Use the `save` option of `ng-add` to configure if the library should be added to the `dependencies`, the `devDepedencies`, or not saved at all in the project's `package.json` configuration file.
+
+<code-example header="projects/my-lib/package.json (ng-add Reference)" path="schematics-for-libraries/projects/my-lib/package.json" region="ng-add">
+</code-example>
+
+Possible values are:
+
+  * `false` - Don't add the package to package.json
+  * `true` - Add the package to the dependencies
+  * `"dependencies"` - Add the package to the dependencies
+  * `"devDependencies"` - Add the package to the devDependencies
+
 ## Building your schematics
 
 To bundle your schematics together with your library, you must configure the library to build the schematics separately, then add them to the bundle.
@@ -115,10 +129,10 @@ When you add a schematic to the collection, you have to point to it in the colle
 <code-example header="projects/my-lib/schematics/my-service/schema.json (Schematic JSON Schema)" path="schematics-for-libraries/projects/my-lib/schematics/my-service/schema.json">
 </code-example>
 
-  * *id* : A unique id for the schema in the collection.
-  * *title* : A human-readable description of the schema.
-  * *type* : A descriptor for the type provided by the properties.
-  * *properties* : An object that defines the available options for the schematic.
+  * *id*: A unique id for the schema in the collection.
+  * *title*: A human-readable description of the schema.
+  * *type*: A descriptor for the type provided by the properties.
+  * *properties*: An object that defines the available options for the schematic.
 
   Each option associates key with a type, description, and optional alias.
   The type defines the shape of the value you expect, and the description is displayed when the user requests usage help for your schematic.
@@ -130,9 +144,9 @@ When you add a schematic to the collection, you have to point to it in the colle
 <code-example header="projects/my-lib/schematics/my-service/schema.ts (Schematic Interface)" path="schematics-for-libraries/projects/my-lib/schematics/my-service/schema.ts">
 </code-example>
 
-  * *name* : The name you want to provide for the created service.
-  * *path* : Overrides the path provided to the schematic. The default path value is based on the current working directory.
-  * *project* : Provides a specific project to run the schematic on. In the schematic, you can provide a default if the option is not provided by the user.
+  * *name*: The name you want to provide for the created service.
+  * *path*: Overrides the path provided to the schematic. The default path value is based on the current working directory.
+  * *project*: Provides a specific project to run the schematic on. In the schematic, you can provide a default if the option is not provided by the user.
 
 ### Add template files
 
@@ -169,10 +183,9 @@ The Schematics framework provides a file templating system, which supports both
 The system operates on placeholders defined inside files or paths that loaded in the input `Tree`.
 It fills these in using values passed into the `Rule`.
 
-For details of these data structure and syntax, see the [Schematics README](https://github.com/angular/angular-cli/blob/master/packages/angular_devkit/schematics/README.md).
+For details of these data structures and syntax, see the [Schematics README](https://github.com/angular/angular-cli/blob/master/packages/angular_devkit/schematics/README.md).
 
-
-1. Create the main file, `index.ts` and add the source code for your schematic factory function.
+1. Create the main file `index.ts` and add the source code for your schematic factory function.
 
 1. First, import the schematics definitions you will need. The Schematics framework offers many utility functions to create and use rules when running a schematic.
 
@@ -271,7 +284,6 @@ For more information about rules and utility methods, see [Provided Rules](https
 
 After you build your library and schematics, you can install the schematics collection to run against your project. The steps below show you how to generate a service using the schematic you created above.
 
-
 ### Build your library and schematics
 
 From the root of your workspace, run the `ng build` command for your library.

aio/content/guide/service-worker-communications.md

@@ -31,28 +31,27 @@ You can use these events to notify the user of a pending update or to refresh th
 
 ### Checking for updates
 
-It's possible to ask the service worker to check if any updates have been deployed to the server. You might choose to do this if you have a site that changes frequently or want updates to happen on a schedule.
+It's possible to ask the service worker to check if any updates have been deployed to the server.
+The service worker checks for updates during initialization and on each navigation request—that is, when the user navigates from a different address to your app.
+However, you might choose to manually check for updates if you have a site that changes frequently or want updates to happen on a schedule.
 
 Do this with the `checkForUpdate()` method:
 
 <code-example path="service-worker-getting-started/src/app/check-for-update.service.ts" header="check-for-update.service.ts"></code-example>
 
-
 This method returns a `Promise` which indicates that the update check has completed successfully, though it does not indicate whether an update was discovered as a result of the check. Even if one is found, the service worker must still successfully download the changed files, which can fail. If successful, the `available` event will indicate availability of a new version of the app.
 
 <div class="alert is-important">
 
-In order to avoid negatively affecting the initial rendering, `ServiceWorkerModule` will by default
-wait for the app to stabilize, before registering the ServiceWorker script. Constantly polling for
-updates, e.g. with `interval()`, will prevent the app from stabilizing and the ServiceWorker
-script will never be registered with the browser.
-
-You can avoid that by waiting for the app to stabilize first, before starting to poll for updates
-(as shown in the example above).
+In order to avoid negatively affecting the initial rendering of the page, `ServiceWorkerModule` waits for up to 30 seconds by default for the app to stabilize, before registering the ServiceWorker script.
+Constantly polling for updates, for example, with [setInterval()](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/setInterval) or RxJS' [interval()](https://rxjs.dev/api/index/function/interval), will prevent the app from stabilizing and the ServiceWorker script will not be registered with the browser until the 30 seconds upper limit is reached.
 
 Note that this is true for any kind of polling done by your application.
 Check the {@link ApplicationRef#isStable isStable} documentation for more information.
 
+You can avoid that delay by waiting for the app to stabilize first, before starting to poll for updates, as shown in the example above.
+Alternatively, you might want to define a different {@link SwRegistrationOptions#registrationStrategy registration strategy} for the ServiceWorker.
+
 </div>
 
 ### Forcing update activation
@@ -61,7 +60,12 @@ If the current tab needs to be updated to the latest app version immediately, it
 
 <code-example path="service-worker-getting-started/src/app/prompt-update.service.ts" header="prompt-update.service.ts" region="sw-activate"></code-example>
 
-Doing this could break lazy-loading in currently running apps, especially if the lazy-loaded chunks use filenames with hashes, which change every version.
+<div class="alert is-important">
+
+Calling `activateUpdate()` without reloading the page could break lazy-loading in a currently running app, especially if the lazy-loaded chunks use filenames with hashes, which change every version.
+Therefore, it is recommended to reload the page once the promise returned by `activateUpdate()` is resolved.
+
+</div>
 
 ## More on Angular service workers
 

aio/content/guide/setup-local.md

@@ -25,49 +25,48 @@ To use the Angular framework, you should be familiar with the following:
 
 Knowledge of [TypeScript](https://www.typescriptlang.org/) is helpful, but not required.
 
+To install Angular on your local system, you need the following:
+
 {@a nodejs}
-### Node.js
 
-Make sure your development environment includes `Node.js®` and an npm package manager.
+* **Node.js**
+  
+  Angular requires a [current, active LTS, or maintenance LTS](https://nodejs.org/about/releases) version of Node.js.
 
-Angular requires a [current, active LTS, or maintenance LTS](https://nodejs.org/about/releases/) version of `Node.js`. See the `engines` key for the specific version requirements in our [package.json](https://unpkg.com/@angular/cli/package.json).
+  <div class="alert is-helpful">
 
-* To check your version, run `node -v` in a terminal/console window.
+  For information about specific version requirements, see the `engines` key in the [package.json](https://unpkg.com/@angular/cli/package.json) file.
 
-* To get `Node.js`, go to [nodejs.org](https://nodejs.org "Nodejs.org").
+  </div>
+
+  For more information on installing Node.js, see [nodejs.org](http://nodejs.org "Nodejs.org").
+  If you are unsure what version of Node.js runs on your system, run `node -v` in a terminal window.
 
 {@a npm}
-### npm package manager
 
-Angular, the Angular CLI, and Angular apps depend on features and functionality provided by libraries that are available as [npm packages](https://docs.npmjs.com/getting-started/what-is-npm). To download and install npm packages, you must have an npm package manager.
+* **npm package manager**
 
-This setup guide uses the [npm client](https://docs.npmjs.com/cli/install) command line interface, which is installed with `Node.js` by default.
-
-To check that you have the npm client installed, run `npm -v` in a terminal/console window.
+  Angular, the Angular CLI, and Angular applications depend on [npm packages](https://docs.npmjs.com/getting-started/what-is-npm) for many features and functions.
+  To download and install npm packages, you need an npm package manager.
+  This guide uses the [npm client](https://docs.npmjs.com/cli/install) command line interface, which is installed with `Node.js` by default.
+  To check that you have the npm client installed, run `npm -v` in a terminal window.
 
 
 {@a install-cli}
 
-## Step 1: Install the Angular CLI
+## Install the Angular CLI
 
-You use the Angular CLI
-to create projects, generate application and library code, and perform a variety of ongoing development tasks such as testing, bundling, and deployment.
-
-Install the Angular CLI globally.
-
-To install the CLI using `npm`, open a terminal/console window and enter the following command:
+You use the Angular CLI to create projects, generate application and library code, and perform a variety of ongoing development tasks such as testing, bundling, and deployment.
 
+To install the Angular CLI, open a terminal window and run the following command:
 
 <code-example language="sh" class="code-shell">
   npm install -g @angular/cli
-
 </code-example>
 
-
-
 {@a create-proj}
 
-## Step 2: Create a workspace and initial application
+## Create a workspace and initial application
 
 You develop apps in the context of an Angular [**workspace**](guide/glossary#workspace).
 
@@ -86,16 +85,22 @@ The Angular CLI installs the necessary Angular npm packages and other dependenci
 
 The CLI creates a new workspace and a simple Welcome app, ready to run.
 
+<div class="alert is-helpful">
+
+You also have the option to use Angular's strict mode, which can help you write better, more maintainable code.
+For more information, see [Strict mode](/guide/strict-mode).
+
+</div>
 
 {@a serve}
 
-## Step 3: Run the application
+## Run the application
 
-The Angular CLI includes a server, so that you can easily build and serve your app locally.
+The Angular CLI includes a server, so that you can build and serve your app locally.
 
-1. Go to the workspace folder (`my-app`).
+1. Navigate to the workspace folder, such as `my-app`.
 
-1. Launch the server by using the CLI command `ng serve`, with the `--open` option.
+1. Run the following command:
 
 <code-example language="sh" class="code-shell">
   cd my-app
@@ -108,7 +113,7 @@ and rebuilds the app as you make changes to those files.
 The `--open` (or just `-o`) option automatically opens your browser
 to `http://localhost:4200/`.
 
-You will see:
+If your installation and setup was successful, you should see a page similar to the following.
 
 
 <div class="lightbox">

aio/content/guide/strict-mode.md

@@ -0,0 +1,46 @@
+# Strict mode
+
+When you create a new workspace or a project you have an option to create them in a strict mode using the `--strict` flag.
+
+Enabling this flag initializes your new workspace or project with a few new settings that improve maintainability, help you catch bugs ahead of time, and allow the CLI to perform advanced optimizations on your application.
+Additionally, applications that use these stricter settings are easier to statically analyze, which can help the `ng update` command refactor code more safely and precisely when you are updating to future versions of Angular.
+
+Specifically, the `strict` flag does the following:
+
+* Enables [`strict` mode in TypeScript](https://www.staging-typescript.org/tsconfig#strict), as well as other strictness flags recommended by the TypeScript team. Specifically, `forceConsistentCasingInFileNames`, `noImplicitReturns`,  `noFallthroughCasesInSwitch`.
+* Turns on strict Angular compiler flags [`strictTemplates`](guide/angular-compiler-options#stricttemplates) and [`strictInjectionParameters`](guide/angular-compiler-options#strictinjectionparameters)
+* [Bundle size budgets](guide/build#configuring-size-budgets) have been reduced by ~75%
+* Turns on [`no-any` tslint rule](https://palantir.github.io/tslint/rules/no-any/) to prevent declarations of type `any`
+* [Marks your application as side-effect free](https://webpack.js.org/guides/tree-shaking/#mark-the-file-as-side-effect-free) to enable more advanced tree-shaking
+
+You can apply these settings at the workspace and project level.
+
+To create a new workspace and application using the strict mode, run the following command:
+
+<code-example language="sh" class="code-shell">
+
+ng new [project-name] --strict
+
+</code-example>
+
+To create a new application in the strict mode within an existing non-strict workspace, run the following command:
+
+<code-example language="sh" class="code-shell">
+
+ng generate application [project-name] --strict
+
+</code-example>
+
+{@a side-effect}
+
+### Non-local side effects in applications
+
+When you create projects and workspaces using the `strict` mode, you'll notice an additional `package.json` file, located in `src/app/` directory.
+This file informs tools and bundlers that the code under this directory is free of non-local side effects. Non-local side effects in the application code are not common and using them is not considered a good coding pattern.
+More importantly, code with these types of side effects cannot be optimized, resulting in increased bundle sizes and applications that load more slowly.
+
+If you need more information, the following links may be helpful.
+
+* [Tree-shaking](https://webpack.js.org/guides/tree-shaking/)
+* [Dealing with side effects and pure functions in JavaScript](https://dev.to/vonheikemen/dealing-with-side-effects-and-pure-functions-in-javascript-16mg)
+* [How to deal with dirty side effects in your pure function JavaScript](https://jrsinclair.com/articles/2018/how-to-deal-with-dirty-side-effects-in-your-pure-functional-javascript/)

aio/content/guide/structural-directives.md

@@ -39,14 +39,14 @@ No brackets. No parentheses. Just `*ngIf` set to a string.
 
 You'll learn in this guide that the [asterisk (*) is a convenience notation](guide/structural-directives#asterisk)
 and the string is a [_microsyntax_](guide/structural-directives#microsyntax) rather than the usual
-[template expression](guide/template-syntax#template-expressions).
+[template expression](guide/interpolation#template-expressions).
 Angular desugars this notation into a marked-up `<ng-template>` that surrounds the
-host element and its descendents.
+host element and its descendants.
 Each structural directive does something different with that template.
 
-Three of the common, built-in structural directives&mdash;[NgIf](guide/template-syntax#ngIf),
-[NgFor](guide/template-syntax#ngFor), and [NgSwitch...](guide/template-syntax#ngSwitch)&mdash;are
-described in the [_Template Syntax_](guide/template-syntax) guide and seen in samples throughout the Angular documentation.
+Three of the common, built-in structural directives&mdash;[NgIf](guide/built-in-directives#ngIf),
+[NgFor](guide/built-in-directives#ngFor), and [NgSwitch...](guide/built-in-directives#ngSwitch)&mdash;are
+described in the [Built-in directives](guide/built-in-directives) guide and seen in samples throughout the Angular documentation.
 Here's an example of them in a template:
 
 
@@ -96,7 +96,7 @@ Technically it's a directive with a template.
 
 An [*attribute* directive](guide/attribute-directives) changes the appearance or behavior
 of an element, component, or another directive.
-For example, the built-in [`NgStyle`](guide/template-syntax#ngStyle) directive
+For example, the built-in [`NgStyle`](guide/built-in-directives#ngStyle) directive
 changes several element styles at the same time.
 
 You can apply many _attribute_ directives to one host element.
@@ -440,7 +440,7 @@ There are several such variables in this example: `hero`, `i`, and `odd`.
 All are preceded by the keyword `let`.
 
 A _template input variable_ is **_not_** the same as a
-[template _reference_ variable](guide/template-syntax#ref-vars),
+[template _reference_ variable](guide/template-reference-variables),
 neither _semantically_ nor _syntactically_.
 
 You declare a template _input_ variable using the `let` keyword (`let hero`).
@@ -786,7 +786,7 @@ That means the directive needs an `appUnless` property, decorated with `@Input`
 
 
 
-Read about `@Input` in the [_Template Syntax_](guide/template-syntax#inputs-outputs) guide.
+Read about `@Input` in the [`@Input()` and `@Output()` properties](guide/inputs-outputs) guide.
 
 
 </div>
@@ -879,12 +879,14 @@ export type LoadingState<T> = Loaded<T> | Loading;
 export class IfLoadedDirective<T> {
     @Input('ifLoaded') set state(state: LoadingState<T>) {}
     static ngTemplateGuard_state<T>(dir: IfLoadedDirective<T>, expr: LoadingState<T>): expr is Loaded<T> { return true; };
+}
+
 export interface Person {
   name: string;
 }
 
 @Component({
-  template: `<div *ifLoaded="state">{{ state.data }}</div>`,
+  template: `&lt;div *ifLoaded="state">{{ state.data }}&lt;/div>`,
 })
 export class AppComponent {
   state: LoadingState<Person>;

aio/content/guide/styleguide.md

@@ -3286,7 +3286,7 @@ helps instantly identify which members of the component serve which purpose.
 
 
 
-**Why?** Angular allows for an [alternative syntax](guide/template-syntax#binding-syntax) `on-*`. If the event itself was prefixed with `on` this would result in an `on-onEvent` binding expression.
+**Why?** Angular allows for an [alternative syntax](guide/binding-syntax) `on-*`. If the event itself was prefixed with `on` this would result in an `on-onEvent` binding expression.
 
 
 </div>

aio/content/guide/svg-in-templates.md

@@ -0,0 +1,27 @@
+# SVG in templates
+
+It is possible to use SVG as valid templates in Angular. All of the template syntax below is
+applicable to both SVG and HTML. Learn more in the SVG [1.1](https://www.w3.org/TR/SVG11/) and
+[2.0](https://www.w3.org/TR/SVG2/) specifications.
+
+<div class="alert is-helpful">
+
+See the <live-example name="template-syntax"></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+Why would you use SVG as template, instead of simply adding it as image to your application?
+
+When you use an SVG as the template, you are able to use directives and bindings just like with HTML
+templates. This means that you will be able to dynamically generate interactive graphics.
+
+Refer to the sample code snippet below for a syntax example:
+
+<code-example path="template-syntax/src/app/svg.component.ts" header="src/app/svg.component.ts"></code-example>
+
+Add the following code to your `svg.component.svg` file:
+
+<code-example path="template-syntax/src/app/svg.component.svg" header="src/app/svg.component.svg"></code-example>
+
+Here you can see the use of a `click()` event binding and the property binding syntax
+(`[attr.fill]="fillColor"`).

aio/content/guide/template-expression-operators.md

@@ -0,0 +1,144 @@
+<!-- {@a expression-operators} -->
+
+# Template expression operators
+
+The Angular template expression language employs a subset of JavaScript syntax supplemented with a few special operators
+for specific scenarios. The next sections cover three of these operators:
+
+* [pipe](guide/template-expression-operators#pipe)
+* [safe navigation operator](guide/template-expression-operators#safe-navigation-operator)
+* [non-null assertion operator](guide/template-expression-operators#non-null-assertion-operator)
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+{@a pipe}
+
+## The pipe operator (`|`)
+
+The result of an expression might require some transformation before you're ready to use it in a binding.
+For example, you might display a number as a currency, change text to uppercase, or filter a list and sort it.
+
+Pipes are simple functions that accept an input value and return a transformed value.
+They're easy to apply within template expressions, using the pipe operator (`|`):
+
+<code-example path="template-expression-operators/src/app/app.component.html" region="uppercase-pipe" header="src/app/app.component.html"></code-example>
+
+The pipe operator passes the result of an expression on the left to a pipe function on the right.
+
+You can chain expressions through multiple pipes:
+
+<code-example path="template-expression-operators/src/app/app.component.html" region="pipe-chain" header="src/app/app.component.html"></code-example>
+
+And you can also [apply parameters](guide/pipes#parameterizing-a-pipe) to a pipe:
+
+<code-example path="template-expression-operators/src/app/app.component.html" region="date-pipe" header="src/app/app.component.html"></code-example>
+
+The `json` pipe is particularly helpful for debugging bindings:
+
+<code-example path="template-expression-operators/src/app/app.component.html" region="json-pipe" header="src/app/app.component.html"></code-example>
+
+The generated output would look something like this:
+
+<code-example language="json">
+  { "name": "Telephone",
+    "manufactureDate": "1980-02-25T05:00:00.000Z",
+    "price": 98 }
+</code-example>
+
+<div class="alert is-helpful">
+
+The pipe operator has a higher precedence than the ternary operator (`?:`),
+which means `a ? b : c | x` is parsed as `a ? b : (c | x)`.
+Nevertheless, for a number of reasons,
+the pipe operator cannot be used without parentheses in the first and second operands of `?:`.
+A good practice is to use parentheses in the third operand too.
+
+</div>
+
+
+<hr/>
+
+{@a safe-navigation-operator}
+
+## The safe navigation operator ( `?` ) and null property paths
+
+The Angular safe navigation operator, `?`, guards against `null` and `undefined`
+values in property paths. Here, it protects against a view render failure if `item` is `null`.
+
+<code-example path="template-expression-operators/src/app/app.component.html" region="safe" header="src/app/app.component.html"></code-example>
+
+If `item` is `null`, the view still renders but the displayed value is blank; you see only "The item name is:" with nothing after it.
+
+Consider the next example, with a `nullItem`.
+
+<code-example language="html">
+  The null item name is {{nullItem.name}}
+</code-example>
+
+Since there is no safe navigation operator and `nullItem` is `null`, JavaScript and Angular would throw a `null` reference error and break the rendering process of Angular:
+
+<code-example language="bash">
+  TypeError: Cannot read property 'name' of null.
+</code-example>
+
+Sometimes however, `null` values in the property
+path may be OK under certain circumstances,
+especially when the value starts out null but the data arrives eventually.
+
+With the safe navigation operator, `?`, Angular stops evaluating the expression when it hits the first `null` value and renders the view without errors.
+
+It works perfectly with long property paths such as `a?.b?.c?.d`.
+
+
+<hr/>
+
+{@a non-null-assertion-operator}
+
+## The non-null assertion operator ( `!` )
+
+As of Typescript 2.0, you can enforce [strict null checking](http://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-0.html "Strict null checking in TypeScript") with the `--strictNullChecks` flag. TypeScript then ensures that no variable is unintentionally `null` or `undefined`.
+
+In this mode, typed variables disallow `null` and `undefined` by default. The type checker throws an error if you leave a variable unassigned or try to assign `null` or `undefined` to a variable whose type disallows `null` and `undefined`.
+
+The type checker also throws an error if it can't determine whether a variable will be `null` or `undefined` at runtime. You tell the type checker not to throw an error by applying the postfix
+[non-null assertion operator, !](http://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-0.html#non-null-assertion-operator "Non-null assertion operator").
+
+The Angular non-null assertion operator, `!`, serves the same purpose in
+an Angular template. For example, you can assert that `item` properties are also defined.
+
+<code-example path="template-expression-operators/src/app/app.component.html" region="non-null" header="src/app/app.component.html"></code-example>
+
+When the Angular compiler turns your template into TypeScript code,
+it prevents TypeScript from reporting that `item.color` might be `null` or `undefined`.
+
+Unlike the [_safe navigation operator_](guide/template-expression-operators#safe-navigation-operator "Safe navigation operator (?)"),
+the non-null assertion operator does not guard against `null` or `undefined`.
+Rather, it tells the TypeScript type checker to suspend strict `null` checks for a specific property expression.
+
+The non-null assertion operator, `!`, is optional with the exception that you must use it when you turn on strict null checks.
+
+{@a any-type-cast-function}
+
+## The `$any()` type cast function
+
+Sometimes a binding expression triggers a type error during [AOT compilation](guide/aot-compiler) and it is not possible or difficult to fully specify the type.
+To silence the error, you can use the `$any()` cast function to cast
+the expression to the [`any` type](http://www.typescriptlang.org/docs/handbook/basic-types.html#any) as in the following example:
+
+<code-example path="built-in-template-functions/src/app/app.component.html" region="any-type-cast-function-1" header="src/app/app.component.html"></code-example>
+
+When the Angular compiler turns this template into TypeScript code,
+it prevents TypeScript from reporting that `bestByDate` is not a member of the `item`
+object when it runs type checking on the template.
+
+The `$any()` cast function also works with `this` to allow access to undeclared members of
+the component.
+
+<code-example path="built-in-template-functions/src/app/app.component.html" region="any-type-cast-function-2" header="src/app/app.component.html"></code-example>
+
+The `$any()` cast function works anywhere in a binding expression where a method call is valid.
+

aio/content/guide/template-reference-variables.md

@@ -0,0 +1,69 @@
+# Template reference variables (`#var`)
+
+A **template reference variable** is often a reference to a DOM element within a template.
+It can also refer to a directive (which contains a component), an element, [TemplateRef](api/core/TemplateRef), or a <a href="https://developer.mozilla.org/en-US/docs/Web/Web_Components" title="MDN: Web Components">web component</a>.
+
+<div class="alert is-helpful">
+
+See the <live-example></live-example> for a working example containing the code snippets in this guide.
+
+</div>
+
+Use the hash symbol (#) to declare a reference variable.
+The following reference variable, `#phone`, declares a `phone` variable on an `<input>` element.
+
+<code-example path="template-reference-variables/src/app/app.component.html" region="ref-var" header="src/app/app.component.html"></code-example>
+
+You can refer to a template reference variable anywhere in the component's template.
+Here, a `<button>` further down the template refers to the `phone` variable.
+
+<code-example path="template-reference-variables/src/app/app.component.html" region="ref-phone" header="src/app/app.component.html"></code-example>
+
+Angular assigns each template reference variable a value based on where you declare the variable:
+
+* If you declare the variable on a component, the variable refers to the component instance.
+* If you declare the variable on a standard HTML tag, the variable refers to the element.
+* If you declare the variable on an `<ng-template>` element, the variable refers to a `TemplateRef` instance, which represents the template.
+* If the variable specifies a name on the right-hand side, such as `#var="ngModel"`, the variable refers to the directive or component on the element with a matching `exportAs` name.
+
+<h3 class="no-toc">How a reference variable gets its value</h3>
+
+In most cases, Angular sets the reference variable's value to the element on which it is declared.
+In the previous example, `phone` refers to the phone number `<input>`.
+The button's click handler passes the `<input>` value to the component's `callPhone()` method.
+
+The `NgForm` directive can change that behavior and set the value to something else. In the following example, the template reference variable, `itemForm`, appears three times separated
+by HTML.
+
+<code-example path="template-reference-variables/src/app/app.component.html" region="ngForm" header="src/app/hero-form.component.html"></code-example>
+
+The reference value of itemForm, without the ngForm attribute value, would be
+the [HTMLFormElement](https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement).
+There is, however, a difference between a Component and a Directive in that a `Component`
+will be referenced without specifying the attribute value, and a `Directive` will not
+change the implicit reference (that is, the element).
+
+
+
+However, with `NgForm`, `itemForm` is a reference to the [NgForm](api/forms/NgForm "API: NgForm")
+directive with the ability to track the value and validity of every control in the form.
+
+The native `<form>` element doesn't have a `form` property, but the `NgForm` directive does, which allows disabling the submit button
+if the `itemForm.form.valid` is invalid and passing the entire form control tree
+to the parent component's `onSubmit()` method.
+
+<h3 class="no-toc">Template reference variable considerations</h3>
+
+A template _reference_ variable (`#phone`) is not the same as a template _input_ variable (`let phone`) such as in an [`*ngFor`](guide/built-in-directives#template-input-variable).
+See [_Structural directives_](guide/structural-directives#template-input-variable) for more information.
+
+The scope of a reference variable is the entire template. So, don't define the same variable name more than once in the same template as the runtime value will be unpredictable.
+
+### Alternative syntax
+
+You can use the `ref-` prefix alternative to `#`.
+This example declares the `fax` variable as `ref-fax` instead of `#fax`.
+
+
+<code-example path="template-reference-variables/src/app/app.component.html" region="ref-fax" header="src/app/app.component.html"></code-example>
+

aio/content/guide/template-statements.md

@@ -0,0 +1,65 @@
+# Template statements
+
+A template **statement** responds to an **event** raised by a binding target
+such as an element, component, or directive.
+
+<div class="alert is-helpful">
+
+See the <live-example name="template-syntax">Template syntax</live-example> for
+the syntax and code snippets in this guide.
+
+</div>
+
+The following template statement appears in quotes to the right of the `=`&nbsp;symbol as in `(event)="statement"`.
+
+<code-example path="template-syntax/src/app/app.component.html" region="context-component-statement" header="src/app/app.component.html"></code-example>
+
+A template statement *has a side effect*.
+That's the whole point of an event.
+It's how you update application state from user action.
+
+Responding to events is the other side of Angular's "unidirectional data flow".
+You're free to change anything, anywhere, during this turn of the event loop.
+
+Like template expressions, template *statements* use a language that looks like JavaScript.
+The template statement parser differs from the template expression parser and
+specifically supports both basic assignment (`=`) and chaining expressions with <code>;</code>.
+
+However, certain JavaScript and template expression syntax is not allowed:
+
+* <code>new</code>
+* increment and decrement operators, `++` and `--`
+* operator assignment, such as `+=` and `-=`
+* the bitwise operators, such as `|` and `&`
+* the [pipe operator](guide/template-expression-operators#pipe)
+
+## Statement context
+
+As with expressions, statements can refer only to what's in the statement context
+such as an event handling method of the component instance.
+
+The *statement context* is typically the component instance.
+The *deleteHero* in `(click)="deleteHero()"` is a method of the data-bound component.
+
+<code-example path="template-syntax/src/app/app.component.html" region="context-component-statement" header="src/app/app.component.html"></code-example>
+
+The statement context may also refer to properties of the template's own context.
+In the following examples, the template `$event` object,
+a [template input variable](guide/built-in-directives#template-input-variable) (`let hero`),
+and a [template reference variable](guide/template-reference-variables) (`#heroForm`)
+are passed to an event handling method of the component.
+
+<code-example path="template-syntax/src/app/app.component.html" region="context-var-statement" header="src/app/app.component.html"></code-example>
+
+Template context names take precedence over component context names.
+In `deleteHero(hero)` above, the `hero` is the template input variable,
+not the component's `hero` property.
+
+## Statement guidelines
+
+Template statements cannot refer to anything in the global namespace. They
+can't refer to `window` or `document`.
+They can't call `console.log` or `Math.max`.
+
+As with expressions, avoid writing complex template statements.
+A method call or simple property assignment should be the norm.

aio/content/guide/template-typecheck.md

@@ -3,7 +3,7 @@
 ## Overview of template type checking
 
 Just as TypeScript catches type errors in your code, Angular checks the expressions and bindings within the templates of your application and can report any type errors it finds.
-Angular currently has three modes of doing this, depending on the value of the `fullTemplateTypeCheck` and `strictTemplates` flags in the [TypeScript configuration file](guide/typescript-configuration), `tsconfig.json`.
+Angular currently has three modes of doing this, depending on the value of the `fullTemplateTypeCheck` and `strictTemplates` flags in the [TypeScript configuration file](guide/typescript-configuration).
 
 ### Basic mode
 
@@ -106,7 +106,7 @@ There can also be false positives when the typings of an Angular library are eit
 
 In case of a false positive like these, there are a few options:
 
-* Use the [`$any()` type-cast function](guide/template-syntax#any-type-cast-function) in certain contexts to opt out of type-checking for a part of the expression.
+* Use the [`$any()` type-cast function](guide/template-expression-operators#any-type-cast-function) in certain contexts to opt out of type-checking for a part of the expression.
 * You can disable strict checks entirely by setting `strictTemplates: false` in the application's TypeScript configuration file, `tsconfig.json`.
 * You can disable certain type-checking operations individually, while maintaining strictness in other aspects, by setting a _strictness flag_ to `false`.
 * If you want to use `strictTemplates` and `strictNullChecks` together, you can opt out of strict null type checking specifically for input bindings via `strictNullInputTypes`.
@@ -286,7 +286,7 @@ Care should be taken that if an `ngAcceptInputType_` override is present for a g
 
 ## Disabling type checking using `$any()`
 
-Disable checking of a binding expression by surrounding the expression in a call to the [`$any()` cast pseudo-function](guide/template-syntax).
+Disable checking of a binding expression by surrounding the expression in a call to the [`$any()` cast pseudo-function](guide/template-expression-operators).
 The compiler treats it as a cast to the `any` type just like in TypeScript when a `<any>` or `as any` cast is used.
 
 In the following example, casting `person` to the `any` type suppresses the error `Property address does not exist`.

aio/content/guide/test-debugging.md

@@ -0,0 +1,28 @@
+# Debugging tests
+
+If your tests aren't working as you expect them to, you can inspect and debug them in the browser.
+
+<div class="alert is-helpful">
+
+  For the sample app that the testing guides describe, see the <live-example name="testing" embedded-style noDownload>sample app</live-example>.
+
+  For the tests features in the testing guides, see <live-example name="testing" stackblitz="specs" noDownload>tests</live-example>.
+
+</div>
+
+
+Debug specs in the browser in the same way that you debug an application.
+
+1. Reveal the Karma browser window. See [Set up testing](guide/testing#set-up-testing) if you need help with this step.
+1. Click the **DEBUG** button; it opens a new browser tab and re-runs the tests.
+1. Open the browser's “Developer Tools” (`Ctrl-Shift-I` on Windows; `Command-Option-I` in macOS).
+1. Pick the "sources" section.
+1. Open the `1st.spec.ts` test file (Control/Command-P, then start typing the name of the file).
+1. Set a breakpoint in the test.
+1. Refresh the browser, and it stops at the breakpoint.
+
+<div class="lightbox">
+  <img src='generated/images/guide/testing/karma-1st-spec-debug.png' alt="Karma debugging">
+</div>
+
+<hr>

aio/content/guide/testing-attribute-directives.md

@@ -0,0 +1,78 @@
+
+{@a attribute-directive}
+
+# Testing Attribute Directives
+
+An _attribute directive_ modifies the behavior of an element, component or another directive.
+Its name reflects the way the directive is applied: as an attribute on a host element.
+
+<div class="alert is-helpful">
+
+  For the sample app that the testing guides describe, see the <live-example name="testing" embedded-style noDownload>sample app</live-example>.
+
+  For the tests features in the testing guides, see <live-example name="testing" stackblitz="specs" noDownload>tests</live-example>.
+
+</div>
+
+## Testing the `HighlightDirective`
+
+The sample application's `HighlightDirective` sets the background color of an element
+based on either a data bound color or a default color (lightgray).
+It also sets a custom property of the element (`customProperty`) to `true`
+for no reason other than to show that it can.
+
+<code-example path="testing/src/app/shared/highlight.directive.ts" header="app/shared/highlight.directive.ts"></code-example>
+
+It's used throughout the application, perhaps most simply in the `AboutComponent`:
+
+<code-example path="testing/src/app/about/about.component.ts" header="app/about/about.component.ts"></code-example>
+
+Testing the specific use of the `HighlightDirective` within the `AboutComponent` requires only the techniques explored in the ["Nested component tests"](guide/testing-components-scenarios#nested-component-tests) section of [Component testing scenarios](guide/testing-components-scenarios).
+
+<code-example path="testing/src/app/about/about.component.spec.ts" region="tests" header="app/about/about.component.spec.ts"></code-example>
+
+However, testing a single use case is unlikely to explore the full range of a directive's capabilities.
+Finding and testing all components that use the directive is tedious, brittle, and almost as unlikely to afford full coverage.
+
+_Class-only tests_ might be helpful,
+but attribute directives like this one tend to manipulate the DOM.
+Isolated unit tests don't touch the DOM and, therefore,
+do not inspire confidence in the directive's efficacy.
+
+A better solution is to create an artificial test component that demonstrates all ways to apply the directive.
+
+<code-example path="testing/src/app/shared/highlight.directive.spec.ts" region="test-component" header="app/shared/highlight.directive.spec.ts (TestComponent)"></code-example>
+
+<div class="lightbox">
+  <img src='generated/images/guide/testing/highlight-directive-spec.png' alt="HighlightDirective spec in action">
+</div>
+
+<div class="alert is-helpful">
+
+The `<input>` case binds the `HighlightDirective` to the name of a color value in the input box.
+The initial value is the word "cyan" which should be the background color of the input box.
+
+</div>
+
+Here are some tests of this component:
+
+<code-example path="testing/src/app/shared/highlight.directive.spec.ts" region="selected-tests" header="app/shared/highlight.directive.spec.ts (selected tests)"></code-example>
+
+A few techniques are noteworthy:
+
+- The `By.directive` predicate is a great way to get the elements that have this directive _when their element types are unknown_.
+
+- The <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/:not">`:not` pseudo-class</a>
+  in `By.css('h2:not([highlight])')` helps find `<h2>` elements that _do not_ have the directive.
+  `By.css('*:not([highlight])')` finds _any_ element that does not have the directive.
+
+- `DebugElement.styles` affords access to element styles even in the absence of a real browser, thanks to the `DebugElement` abstraction.
+  But feel free to exploit the `nativeElement` when that seems easier or more clear than the abstraction.
+
+- Angular adds a directive to the injector of the element to which it is applied.
+  The test for the default color uses the injector of the second `<h2>` to get its `HighlightDirective` instance
+  and its `defaultColor`.
+
+- `DebugElement.properties` affords access to the artificial custom property that is set by the directive.
+
+<hr>

aio/content/guide/testing-code-coverage.md

@@ -0,0 +1,57 @@
+{@a code-coverage}
+
+# Find out how much code you're testing
+
+The CLI can run unit tests and create code coverage reports.
+Code coverage reports show you any parts of your code base that may not be properly tested by your unit tests.
+
+<div class="alert is-helpful">
+
+  For the sample app that the testing guides describe, see the <live-example name="testing" embedded-style noDownload>sample app</live-example>.
+
+  For the tests features in the testing guides, see <live-example name="testing" stackblitz="specs" noDownload>tests</live-example>.
+
+</div>
+
+
+To generate a coverage report run the following command in the root of your project.
+
+<code-example language="sh" class="code-shell">
+  ng test --no-watch --code-coverage
+</code-example>
+
+When the tests are complete, the command creates a new `/coverage` folder in the project. Open the `index.html` file to see a report with your source code and code coverage values.
+
+If you want to create code-coverage reports every time you test, you can set the following option in the CLI configuration file, `angular.json`:
+
+```
+  "test": {
+    "options": {
+      "codeCoverage": true
+    }
+  }
+```
+
+## Code coverage enforcement
+
+The code coverage percentages let you estimate how much of your code is tested.
+If your team decides on a set minimum amount to be unit tested, you can enforce this minimum with the Angular CLI.
+
+For example, suppose you want the code base to have a minimum of 80% code coverage.
+To enable this, open the [Karma](https://karma-runner.github.io) test platform configuration file, `karma.conf.js`, and add the following in the `coverageIstanbulReporter:` key.
+
+```
+coverageIstanbulReporter: {
+  reports: [ 'html', 'lcovonly' ],
+  fixWebpackSourcePaths: true,
+  thresholds: {
+    statements: 80,
+    lines: 80,
+    branches: 80,
+    functions: 80
+  }
+}
+```
+
+The `thresholds` property causes the tool to enforce a minimum of 80% code coverage when the unit tests are run in the project.
+

aio/content/guide/testing-components-basics.md

@@ -0,0 +1,380 @@
+# Basics of testing components
+
+A component, unlike all other parts of an Angular application,
+combines an HTML template and a TypeScript class.
+The component truly is the template and the class _working together_. To adequately test a component, you should test that they work together
+as intended.
+
+Such tests require creating the component's host element in the browser DOM,
+as Angular does, and investigating the component class's interaction with
+the DOM as described by its template.
+
+The Angular `TestBed` facilitates this kind of testing as you'll see in the sections below.
+But in many cases, _testing the component class alone_, without DOM involvement,
+can validate much of the component's behavior in an easier, more obvious way.
+
+<div class="alert is-helpful">
+
+  For the sample app that the testing guides describe, see the <live-example name="testing" embedded-style noDownload>sample app</live-example>.
+
+  For the tests features in the testing guides, see <live-example name="testing" stackblitz="specs" noDownload>tests</live-example>.
+
+</div>
+
+
+{@a component-class-testing}
+
+## Component class testing
+
+Test a component class on its own as you would test a service class.
+
+Component class testing should be kept very clean and simple.
+It should test only a single unit.
+At first glance, you should be able to understand
+what the test is testing.
+
+Consider this `LightswitchComponent` which toggles a light on and off
+(represented by an on-screen message) when the user clicks the button.
+
+<code-example
+  path="testing/src/app/demo/demo.ts"
+  region="LightswitchComp"
+  header="app/demo/demo.ts (LightswitchComp)"></code-example>
+
+You might decide only to test that the `clicked()` method
+toggles the light's _on/off_ state and sets the message appropriately.
+
+This component class has no dependencies. To test these types of classes, follow the same steps as you would for a service that has no dependencies:
+
+1. Create a component using the new keyword.
+2. Poke at its API.
+3. Assert expectations on its public state.
+
+<code-example
+  path="testing/src/app/demo/demo.spec.ts"
+  region="Lightswitch"
+  header="app/demo/demo.spec.ts (Lightswitch tests)"></code-example>
+
+Here is the `DashboardHeroComponent` from the _Tour of Heroes_ tutorial.
+
+<code-example
+  path="testing/src/app/dashboard/dashboard-hero.component.ts"
+  region="class"
+  header="app/dashboard/dashboard-hero.component.ts (component)"></code-example>
+
+It appears within the template of a parent component,
+which binds a _hero_ to the `@Input` property and
+listens for an event raised through the _selected_ `@Output` property.
+
+You can test that the class code works without creating the `DashboardHeroComponent`
+or its parent component.
+
+<code-example
+  path="testing/src/app/dashboard/dashboard-hero.component.spec.ts"
+  region="class-only"
+  header="app/dashboard/dashboard-hero.component.spec.ts (class tests)"></code-example>
+
+When a component has dependencies, you may wish to use the `TestBed` to both
+create the component and its dependencies.
+
+The following `WelcomeComponent` depends on the `UserService` to know the name of the user to greet.
+
+<code-example
+  path="testing/src/app/welcome/welcome.component.ts"
+  region="class"
+  header="app/welcome/welcome.component.ts"></code-example>
+
+You might start by creating a mock of the `UserService` that meets the minimum needs of this component.
+
+<code-example
+  path="testing/src/app/welcome/welcome.component.spec.ts"
+  region="mock-user-service"
+  header="app/welcome/welcome.component.spec.ts (MockUserService)"></code-example>
+
+Then provide and inject _both the_ **component** _and the service_ in the `TestBed` configuration.
+
+<code-example
+  path="testing/src/app/welcome/welcome.component.spec.ts"
+  region="class-only-before-each"
+  header="app/welcome/welcome.component.spec.ts (class-only setup)"></code-example>
+
+Then exercise the component class, remembering to call the [lifecycle hook methods](guide/lifecycle-hooks) as Angular does when running the app.
+
+<code-example
+  path="testing/src/app/welcome/welcome.component.spec.ts"
+  region="class-only-tests"
+  header="app/welcome/welcome.component.spec.ts (class-only tests)"></code-example>
+
+## Component DOM testing
+
+Testing the component _class_ is as easy as [testing a service](guide/testing-services).
+
+But a component is more than just its class.
+A component interacts with the DOM and with other components.
+The _class-only_ tests can tell you about class behavior.
+They cannot tell you if the component is going to render properly,
+respond to user input and gestures, or integrate with its parent and child components.
+
+None of the _class-only_ tests above can answer key questions about how the
+components actually behave on screen.
+
+- Is `Lightswitch.clicked()` bound to anything such that the user can invoke it?
+- Is the `Lightswitch.message` displayed?
+- Can the user actually select the hero displayed by `DashboardHeroComponent`?
+- Is the hero name displayed as expected (i.e, in uppercase)?
+- Is the welcome message displayed by the template of `WelcomeComponent`?
+
+These may not be troubling questions for the simple components illustrated above.
+But many components have complex interactions with the DOM elements
+described in their templates, causing HTML to appear and disappear as
+the component state changes.
+
+To answer these kinds of questions, you have to create the DOM elements associated
+with the components, you must examine the DOM to confirm that component state
+displays properly at the appropriate times, and you must simulate user interaction
+with the screen to determine whether those interactions cause the component to
+behave as expected.
+
+To write these kinds of test, you'll use additional features of the `TestBed`
+as well as other testing helpers.
+
+### CLI-generated tests
+
+The CLI creates an initial test file for you by default when you ask it to
+generate a new component.
+
+For example, the following CLI command generates a `BannerComponent` in the `app/banner` folder (with inline template and styles):
+
+<code-example language="sh" class="code-shell">
+ng generate component banner --inline-template --inline-style --module app
+</code-example>
+
+It also generates an initial test file for the component, `banner-external.component.spec.ts`, that looks like this:
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="v1"
+  header="app/banner/banner-external.component.spec.ts (initial)"></code-example>
+
+<div class="alert is-helpful">
+
+Because `compileComponents` is asynchronous, it uses
+the [`async`](api/core/testing/async) utility
+function imported from `@angular/core/testing`.
+
+Please refer to the [async](guide/testing-components-scenarios#async) section for more details.
+
+</div>
+
+### Reduce the setup
+
+Only the last three lines of this file actually test the component
+and all they do is assert that Angular can create the component.
+
+The rest of the file is boilerplate setup code anticipating more advanced tests that _might_ become necessary if the component evolves into something substantial.
+
+You'll learn about these advanced test features below.
+For now, you can radically reduce this test file to a more manageable size:
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="v2"
+  header="app/banner/banner-initial.component.spec.ts (minimal)"></code-example>
+
+In this example, the metadata object passed to `TestBed.configureTestingModule`
+simply declares `BannerComponent`, the component to test.
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="configureTestingModule">
+</code-example>
+
+<div class="alert is-helpful">
+
+There's no need to declare or import anything else.
+The default test module is pre-configured with
+something like the `BrowserModule` from `@angular/platform-browser`.
+
+Later you'll call `TestBed.configureTestingModule()` with
+imports, providers, and more declarations to suit your testing needs.
+Optional `override` methods can further fine-tune aspects of the configuration.
+
+</div>
+
+{@a create-component}
+
+### _createComponent()_
+
+After configuring `TestBed`, you call its `createComponent()` method.
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="createComponent">
+</code-example>
+
+`TestBed.createComponent()` creates an instance of the `BannerComponent`,
+adds a corresponding element to the test-runner DOM,
+and returns a [`ComponentFixture`](#component-fixture).
+
+<div class="alert is-important">
+
+Do not re-configure `TestBed` after calling `createComponent`.
+
+The `createComponent` method freezes the current `TestBed` definition,
+closing it to further configuration.
+
+You cannot call any more `TestBed` configuration methods, not `configureTestingModule()`,
+nor `get()`, nor any of the `override...` methods.
+If you try, `TestBed` throws an error.
+
+</div>
+
+{@a component-fixture}
+
+### _ComponentFixture_
+
+The [ComponentFixture](api/core/testing/ComponentFixture) is a test harness for interacting with the created component and its corresponding element.
+
+Access the component instance through the fixture and confirm it exists with a Jasmine expectation:
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="componentInstance">
+</code-example>
+
+### _beforeEach()_
+
+You will add more tests as this component evolves.
+Rather than duplicate the `TestBed` configuration for each test,
+you refactor to pull the setup into a Jasmine `beforeEach()` and some supporting variables:
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="v3"
+ ></code-example>
+
+Now add a test that gets the component's element from `fixture.nativeElement` and
+looks for the expected text.
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="v4-test-2">
+</code-example>
+
+{@a native-element}
+
+### _nativeElement_
+
+The value of `ComponentFixture.nativeElement` has the `any` type.
+Later you'll encounter the `DebugElement.nativeElement` and it too has the `any` type.
+
+Angular can't know at compile time what kind of HTML element the `nativeElement` is or
+if it even is an HTML element.
+The app might be running on a _non-browser platform_, such as the server or a
+[Web Worker](https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API),
+where the element may have a diminished API or not exist at all.
+
+The tests in this guide are designed to run in a browser so a
+`nativeElement` value will always be an `HTMLElement` or
+one of its derived classes.
+
+Knowing that it is an `HTMLElement` of some sort, you can use
+the standard HTML `querySelector` to dive deeper into the element tree.
+
+Here's another test that calls `HTMLElement.querySelector` to get the paragraph element and look for the banner text:
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="v4-test-3">
+</code-example>
+
+{@a debug-element}
+
+### _DebugElement_
+
+The Angular _fixture_ provides the component's element directly through the `fixture.nativeElement`.
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="nativeElement">
+</code-example>
+
+This is actually a convenience method, implemented as `fixture.debugElement.nativeElement`.
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="debugElement-nativeElement">
+</code-example>
+
+There's a good reason for this circuitous path to the element.
+
+The properties of the `nativeElement` depend upon the runtime environment.
+You could be running these tests on a _non-browser_ platform that doesn't have a DOM or
+whose DOM-emulation doesn't support the full `HTMLElement` API.
+
+Angular relies on the `DebugElement` abstraction to work safely across _all supported platforms_.
+Instead of creating an HTML element tree, Angular creates a `DebugElement` tree that wraps the _native elements_ for the runtime platform.
+The `nativeElement` property unwraps the `DebugElement` and returns the platform-specific element object.
+
+Because the sample tests for this guide are designed to run only in a browser,
+a `nativeElement` in these tests is always an `HTMLElement`
+whose familiar methods and properties you can explore within a test.
+
+Here's the previous test, re-implemented with `fixture.debugElement.nativeElement`:
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="v4-test-4">
+</code-example>
+
+The `DebugElement` has other methods and properties that
+are useful in tests, as you'll see elsewhere in this guide.
+
+You import the `DebugElement` symbol from the Angular core library.
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="import-debug-element">
+</code-example>
+
+{@a by-css}
+### _By.css()_
+
+Although the tests in this guide all run in the browser,
+some apps might run on a different platform at least some of the time.
+
+For example, the component might render first on the server as part of a strategy to make the application launch faster on poorly connected devices. The server-side renderer might not support the full HTML element API.
+If it doesn't support `querySelector`, the previous test could fail.
+
+The `DebugElement` offers query methods that work for all supported platforms.
+These query methods take a _predicate_ function that returns `true` when a node in the `DebugElement` tree matches the selection criteria.
+
+You create a _predicate_ with the help of a `By` class imported from a
+library for the runtime platform. Here's the `By` import for the browser platform:
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="import-by">
+</code-example>
+
+The following example re-implements the previous test with
+`DebugElement.query()` and the browser's `By.css` method.
+
+<code-example
+  path="testing/src/app/banner/banner-initial.component.spec.ts"
+  region="v4-test-5">
+</code-example>
+
+Some noteworthy observations:
+
+- The `By.css()` static method selects `DebugElement` nodes
+  with a [standard CSS selector](https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_started/Selectors 'CSS selectors').
+- The query returns a `DebugElement` for the paragraph.
+- You must unwrap that result to get the paragraph element.
+
+When you're filtering by CSS selector and only testing properties of a browser's _native element_, the `By.css` approach may be overkill.
+
+It's often easier and more clear to filter with a standard `HTMLElement` method
+such as `querySelector()` or `querySelectorAll()`,
+as you'll see in the next set of tests.
+

aio/content/guide/testing-pipes.md

@@ -0,0 +1,41 @@
+# Testing Pipes
+
+You can test [pipes](guide/pipes) without the Angular testing utilities.
+
+<div class="alert is-helpful">
+
+  For the sample app that the testing guides describe, see the <live-example name="testing" embedded-style noDownload>sample app</live-example>.
+
+  For the tests features in the testing guides, see <live-example name="testing" stackblitz="specs" noDownload>tests</live-example>.
+
+</div>
+
+## Testing the `TitleCasePipe`
+
+A pipe class has one method, `transform`, that manipulates the input
+value into a transformed output value.
+The `transform` implementation rarely interacts with the DOM.
+Most pipes have no dependence on Angular other than the `@Pipe`
+metadata and an interface.
+
+Consider a `TitleCasePipe` that capitalizes the first letter of each word.
+Here's an implementation with a regular expression.
+
+<code-example path="testing/src/app/shared/title-case.pipe.ts" header="app/shared/title-case.pipe.ts"></code-example>
+
+Anything that uses a regular expression is worth testing thoroughly.
+Use simple Jasmine to explore the expected cases and the edge cases.
+
+<code-example path="testing/src/app/shared/title-case.pipe.spec.ts" region="excerpt" header="app/shared/title-case.pipe.spec.ts"></code-example>
+
+{@a write-tests}
+
+## Writing DOM tests to support a pipe test
+
+These are tests of the pipe _in isolation_.
+They can't tell if the `TitleCasePipe` is working properly as applied in the application components.
+
+Consider adding component tests such as this one:
+
+<code-example path="testing/src/app/hero/hero-detail.component.spec.ts" region="title-case-pipe" header="app/hero/hero-detail.component.spec.ts (pipe test)"></code-example>
+

aio/content/guide/testing-services.md

@@ -0,0 +1,199 @@
+# Testing services
+
+
+To check that your services are working as you intend, you can write tests specifically for them.
+
+<div class="alert is-helpful">
+
+  For the sample app that the testing guides describe, see the <live-example name="testing" embedded-style noDownload>sample app</live-example>.
+
+  For the tests features in the testing guides, see <live-example name="testing" stackblitz="specs" noDownload>tests</live-example>.
+
+</div>
+
+
+Services are often the easiest files to unit test.
+Here are some synchronous and asynchronous unit tests of the `ValueService`
+written without assistance from Angular testing utilities.
+
+<code-example path="testing/src/app/demo/demo.spec.ts" region="ValueService" header="app/demo/demo.spec.ts"></code-example>
+
+{@a services-with-dependencies}
+
+## Services with dependencies
+
+Services often depend on other services that Angular injects into the constructor.
+In many cases, it's easy to create and _inject_ these dependencies by hand while
+calling the service's constructor.
+
+The `MasterService` is a simple example:
+
+<code-example path="testing/src/app/demo/demo.ts" region="MasterService" header="app/demo/demo.ts"></code-example>
+
+`MasterService` delegates its only method, `getValue`, to the injected `ValueService`.
+
+Here are several ways to test it.
+
+<code-example path="testing/src/app/demo/demo.spec.ts" region="MasterService" header="app/demo/demo.spec.ts"></code-example>
+
+The first test creates a `ValueService` with `new` and passes it to the `MasterService` constructor.
+
+However, injecting the real service rarely works well as most dependent services are difficult to create and control.
+
+Instead you can mock the dependency, use a dummy value, or create a
+[spy](https://jasmine.github.io/2.0/introduction.html#section-Spies)
+on the pertinent service method.
+
+<div class="alert is-helpful">
+
+Prefer spies as they are usually the easiest way to mock services.
+
+</div>
+
+These standard testing techniques are great for unit testing services in isolation.
+
+However, you almost always inject services into application classes using Angular
+dependency injection and you should have tests that reflect that usage pattern.
+Angular testing utilities make it easy to investigate how injected services behave.
+
+## Testing services with the _TestBed_
+
+Your app relies on Angular [dependency injection (DI)](guide/dependency-injection)
+to create services.
+When a service has a dependent service, DI finds or creates that dependent service.
+And if that dependent service has its own dependencies, DI finds-or-creates them as well.
+
+As service _consumer_, you don't worry about any of this.
+You don't worry about the order of constructor arguments or how they're created.
+
+As a service _tester_, you must at least think about the first level of service dependencies
+but you _can_ let Angular DI do the service creation and deal with constructor argument order
+when you use the `TestBed` testing utility to provide and create services.
+
+{@a testbed}
+
+## Angular _TestBed_
+
+The `TestBed` is the most important of the Angular testing utilities.
+The `TestBed` creates a dynamically-constructed Angular _test_ module that emulates
+an Angular [@NgModule](guide/ngmodules).
+
+The `TestBed.configureTestingModule()` method takes a metadata object that can have most of the properties of an [@NgModule](guide/ngmodules).
+
+To test a service, you set the `providers` metadata property with an
+array of the services that you'll test or mock.
+
+<code-example path="testing/src/app/demo/demo.testbed.spec.ts" region="value-service-before-each" header="app/demo/demo.testbed.spec.ts (provide ValueService in beforeEach)"></code-example>
+
+Then inject it inside a test by calling `TestBed.inject()` with the service class as the argument.
+
+<div class="alert is-helpful">
+
+**Note:** `TestBed.get()` was deprecated as of Angular version 9.
+To help minimize breaking changes, Angular introduces a new function called `TestBed.inject()`, which you should use instead.
+For information on the removal of `TestBed.get()`,
+see its entry in the [Deprecations index](guide/deprecations#index).
+
+</div>
+
+<code-example path="testing/src/app/demo/demo.testbed.spec.ts" region="value-service-inject-it"></code-example>
+
+Or inside the `beforeEach()` if you prefer to inject the service as part of your setup.
+
+<code-example path="testing/src/app/demo/demo.testbed.spec.ts" region="value-service-inject-before-each"> </code-example>
+
+When testing a service with a dependency, provide the mock in the `providers` array.
+
+In the following example, the mock is a spy object.
+
+<code-example path="testing/src/app/demo/demo.testbed.spec.ts" region="master-service-before-each"></code-example>
+
+The test consumes that spy in the same way it did earlier.
+
+<code-example path="testing/src/app/demo/demo.testbed.spec.ts" region="master-service-it">
+</code-example>
+
+{@a no-before-each}
+
+## Testing without _beforeEach()_
+
+Most test suites in this guide call `beforeEach()` to set the preconditions for each `it()` test
+and rely on the `TestBed` to create classes and inject services.
+
+There's another school of testing that never calls `beforeEach()` and prefers to create classes explicitly rather than use the `TestBed`.
+
+Here's how you might rewrite one of the `MasterService` tests in that style.
+
+Begin by putting re-usable, preparatory code in a _setup_ function instead of `beforeEach()`.
+
+<code-example
+  path="testing/src/app/demo/demo.spec.ts"
+  region="no-before-each-setup"
+  header="app/demo/demo.spec.ts (setup)"></code-example>
+
+The `setup()` function returns an object literal
+with the variables, such as `masterService`, that a test might reference.
+You don't define _semi-global_ variables (e.g., `let masterService: MasterService`)
+in the body of the `describe()`.
+
+Then each test invokes `setup()` in its first line, before continuing
+with steps that manipulate the test subject and assert expectations.
+
+<code-example
+  path="testing/src/app/demo/demo.spec.ts"
+  region="no-before-each-test"></code-example>
+
+Notice how the test uses
+[_destructuring assignment_](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment)
+to extract the setup variables that it needs.
+
+<code-example
+  path="testing/src/app/demo/demo.spec.ts"
+  region="no-before-each-setup-call">
+</code-example>
+
+Many developers feel this approach is cleaner and more explicit than the
+traditional `beforeEach()` style.
+
+Although this testing guide follows the traditional style and
+the default [CLI schematics](https://github.com/angular/angular-cli)
+generate test files with `beforeEach()` and `TestBed`,
+feel free to adopt _this alternative approach_ in your own projects.
+
+## Testing HTTP services
+
+Data services that make HTTP calls to remote servers typically inject and delegate
+to the Angular [`HttpClient`](guide/http) service for XHR calls.
+
+You can test a data service with an injected `HttpClient` spy as you would
+test any service with a dependency.
+<code-example
+  path="testing/src/app/model/hero.service.spec.ts"
+  region="test-with-spies"
+  header="app/model/hero.service.spec.ts (tests with spies)">
+</code-example>
+
+<div class="alert is-important">
+
+The `HeroService` methods return `Observables`. You must
+_subscribe_ to an observable to (a) cause it to execute and (b)
+assert that the method succeeds or fails.
+
+The `subscribe()` method takes a success (`next`) and fail (`error`) callback.
+Make sure you provide _both_ callbacks so that you capture errors.
+Neglecting to do so produces an asynchronous uncaught observable error that
+the test runner will likely attribute to a completely different test.
+
+</div>
+
+## _HttpClientTestingModule_
+
+Extended interactions between a data service and the `HttpClient` can be complex
+and difficult to mock with spies.
+
+The `HttpClientTestingModule` can make these testing scenarios more manageable.
+
+While the _code sample_ accompanying this guide demonstrates `HttpClientTestingModule`,
+this page defers to the [Http guide](guide/http#testing-http-requests),
+which covers testing with the `HttpClientTestingModule` in detail.
+