As mentioned in the previous commit, the regexp used by
`Validators.email()` is a slightly enhanced version of the
[WHATWG one](https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address).
This commit refactors the regexp (without changing its behavior) to make
it more closely match the format of WHATWG version, so that it is easier
for people to compare it against the WHATWG one and understand the
differences.
The main changes were:
- Changing the order of characters/character classes inside `[...]`;
e.g. `[A-Za-z]` --> `[a-zA-Z]`
- Mark all groups as non-capturing (since we do not use the captured
values); e.g. `(foo)` --> `(?:foo)`
(This could theoretically also have a positive performance impact, but
I suspect JavaScript engines are already optimizing away capturing
groups when they are not used.)
PR Close#32961
Previously, there was no documentation of what `Validators.email()`
expects as a valid e-mail address, making it difficult for people to
determine whether it covers their requirements or not. Even more so that
the used pattern slightly deviates from the
[WHATWG version](https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address).
One's only option was to look at the source code and try to decipher the
regexp pattern.
This commit adds a high-level description of the validator and mentions
its similarity to and differences from the WHATWG version. It also adds
a brief explanation of the regexp's behavior and references for more
information in the source code to provide more context to
maintainers/users trying to understand the implementation in the future.
Fixes#18985Fixes#25186Closes#32747
PR Close#32961
Observable subscriptions from previous validation runs should be canceled
before a new subscription is created for the next validation run.
Currently the subscription that sets the errors is canceled properly,
but the source observable created by the validator is not. While this
does not affect validation status or error setting, the source
observables will incorrectly continue through the pipeline until they
complete. This change ensures that the whole stream is canceled.
AsyncValidatorFn previously had an "any" return type, but now it more
explicitly requires a Promise or Observable return type. We don't
anticipate this causing problems given that any other return type
would have caused a runtime error already.
This API was introduced only in a beta release, and is being removed because we found it to be incorrect prior to launch. For more information about why this is being removed, see https://github.com/angular/angular/pull/15050.
