After the introduction of the view engine, we can drop a lot of code that is not used any more.
This should reduce the size of the app bundles because a lot of this code was not being properly tree-shaken by today's tools even though it was dead code.
When the `enableLegacyTemplate` is set to `false`, `<template>` tags and the
`template` attribute are no more used to define angular templates but are
treated as regular tag and attribute.
The default value is `true`.
In order to define a template, you have to use the `<ng-template>` tag.
This option applies to your application and all the libraries it uses. That is
you should make sure none of them rely on the legacy way to defined templates
when this option is turned off (`false`).
The rationale of this change is to improve the inter-operability with web
components that might make use of the `<template>` tag.
DEPRECATION
The template tags and template attribute are deprecated:
<template ngFor [ngFor]=items let-item><li>...</li></template>
<li template="ngFor: let item of items">...</li>
should be rewritten as:
<ng-template ngFor [ngFor]=items let-item><li>...</li></ng-template>
Note that they still be supported in 4.x with a deprecartion warning in
development mode.
MIGRATION
- `template` tags (or elements with a `template` attribute) should be rewritten
as a `ng-template` tag,
- `ng-content` selectors should be updated to referto a `ng-template` where they
use to refer to a template: `<ng-content selector="template[attr]">` should be
rewritten as `<ng-content selector="ng-template[attr]">`
- if you consume a component relying on your templates being actual `template`
elements (that is they include a `<ng-content selector="template[attr]">`). You
should still migrate to `ng-template` and make use of `ngProjectAs` to override
the way `ng-content` sees the template:
`<ng-template projectAs="template[attr]">`
- while `template` elements are deprecated in 4.x they continue to work.
Note that this does not yet include enabling the view engine
by default.
Included refactoring:
- view engine: split namespace of elements / attributes already
when creating the `NodeDef`
- view engine: when injecting the old `Renderer`, use an implementation
that is based on `RendererV2`
- view engine: store view queries in the component view, not
on the host element
- Introduce `InjectionToken<T>` which is a parameterized and type-safe
version of `OpaqueToken`.
DEPRECATION:
- `OpaqueToken` is now deprecated, use `InjectionToken<T>` instead.
- `Injector.get(token: any, notFoundValue?: any): any` is now deprecated
use the same method which is now overloaded as
`Injector.get<T>(token: Type<T>|InjectionToken<T>, notFoundValue?: T): T;`.
Migration
- Replace `OpaqueToken` with `InjectionToken<?>` and parameterize it.
- Migrate your code to only use `Type<?>` or `InjectionToken<?>` as
injection tokens. Using other tokens will not be supported in the
future.
BREAKING CHANGE:
- Because `injector.get()` is now parameterize it is possible that code
which used to work no longer type checks. Example would be if one
injects `Foo` but configures it as `{provide: Foo, useClass: MockFoo}`.
The injection instance will be that of `MockFoo` but the type will be
`Foo` instead of `any` as in the past. This means that it was possible
to call a method on `MockFoo` in the past which now will fail type
check. See this example:
```
class Foo {}
class MockFoo extends Foo {
setupMock();
}
var PROVIDERS = [
{provide: Foo, useClass: MockFoo}
];
...
function myTest(injector: Injector) {
var foo = injector.get(Foo);
// This line used to work since `foo` used to be `any` before this
// change, it will now be `Foo`, and `Foo` does not have `setUpMock()`.
// The fix is to downcast: `injector.get(Foo) as MockFoo`.
foo.setUpMock();
}
```
PR Close#13785
Fixes:
- Inject the i18n specific HtmlParser into the directive normalizer,
- Parse ICU messages while normalizing templates,
- Normalize (visit) the content of ICU messages.
🎄🎁🎅
When compiling libraries, this feature extracts the minimal information
from the directives/pipes/modules of the library into `.ngsummary.json` files,
so that applications that use this library only need to be recompiled
if one of the summary files change, but not on every change
of the libraries (e.g. one of the templates).
Only works if individual codegen for libraries is enabled,
see the `generateCodeForLibraries: false` option.
Closes#12787
