This commit fixes a regression where `ngModel` no longer syncs
letter by letter on Android devices, and instead syncs at the
end of every word. This broke when we introduced buffering of
IME events so IMEs like Pinyin keyboards or Katakana keyboards
wouldn't display composition strings. Unfortunately, iOS devices
and Android devices have opposite event behavior. Whereas iOS
devices fire composition events for IME keyboards only, Android
fires composition events for Latin-language keyboards. For
this reason, languages like English don't work as expected on
Android if we always buffer. So to support both platforms,
composition string buffering will only be turned on by default
for non-Android devices.
However, we have also added a `COMPOSITION_BUFFER_MODE` token
to make this configurable by the application. In some cases, apps
might might still want to receive intermediate values. For example,
some inputs begin searching based on Latin letters before a
character selection is made.
As a provider, this is fairly flexible. If you want to turn
composition buffering off, simply provide the token at the top
level:
```ts
providers: [
{provide: COMPOSITION_BUFFER_MODE, useValue: false}
]
```
Or, if you want to change the mode based on locale or platform,
you can use a factory:
```ts
import {shouldUseBuffering} from 'my/lib';
....
providers: [
{provide: COMPOSITION_BUFFER_MODE, useFactory: shouldUseBuffering}
]
```
Closes#15079.
PR Close#15256
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.
