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refactor(core): remove isObservable TODO (#39669) 

This commit removes the TODO comment that proposed
that we use the built-in RxJS `isObservable()` function.

This is not a viable approach since the built-in function
requires that the `obj` contains additional methods that
our "observable" types (such as `EventEmitter`) do not
necessarily have.

See #39643 for more information.

PR Close #39669
This commit is contained in:
Pete Bacon Darwin 2020-11-13 08:05:17 +00:00 committed by atscott
parent c461acd12e
commit 7bcfc0db09
1 changed files with 6 additions and 2 deletions
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8
packages/core/src/util/lang.ts
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@ -19,9 +19,13 @@ export function isPromise<T = any>(obj: any): obj is Promise<T> {
/** /**
* Determine if the argument is an Observable * Determine if the argument is an Observable
*
* Strictly this tests that the `obj` is `Subscribable`, since `Observable`
* types need additional methods, such as `lift()`. But it is adequate for our
* needs since within the Angular framework code we only ever need to use the
* `subscribe()` method, and RxJS has mechanisms to wrap `Subscribable` objects
* into `Observable` as needed.
*/ */
export function isObservable(obj: any|Observable<any>): obj is Observable<any> { export function isObservable(obj: any|Observable<any>): obj is Observable<any> {
// TODO: use isObservable once we update pass rxjs 6.1
// https://github.com/ReactiveX/rxjs/blob/master/CHANGELOG.md#610-2018-05-03
return !!obj && typeof obj.subscribe === 'function'; return !!obj && typeof obj.subscribe === 'function';
} }