What functionalities that RxJS provide for Angular2?

Question

There is some references of RxJS in the Angular2 project. What is RxJS being used for in Angular2?

Answer 1

A list of what angular2 uses RxJS for

• Http (for example its get method returns an Observable)
• EventEmitter (like you said, extends from Subject)
• AsyncPipe which supports Promise, Observable or EventEmitter.
• QueryList's changes method returns an EventEmitter. Update
• NG_ASYNC_VALIDATORS which implements Validator and overrides the method validate to return either a Promise or an Observable. Update

Note about NG_ASYNC_VALIDATORS

NG_ASYNC_VALIDATORS doesn't use Observable directly, it doesn't subscribe to them but converts them to Promises, in any case, NG_ASYNC_VALIDATORS still accepts Observables. Look at line #104 in validators.ts.

Thanks to @przemcio for the observation.

Not yet implemented / In conversation

• ObserveChild which would return an EventEmitter.
• ObserveChildren Update

Note

They are working on bundle RxJS with the bare operators, see issue #5288. The idea is to distribute angular2 with the minimal required operators and make the user to provide the rest of them.

Note update

Like I was told here and here (I had a problem with importing Subject) they're working on removing completely Subject, so from core we would be able to import only Observable, everything else should be provided by the developer.

PS

I can't think of any other, if I remember of something else I'll update the answer.