Return an empty Observable

Question

For typescript you can specify generic param of your empty observable like this:

import 'rxjs/add/observable/empty' 

Observable.empty<Response>();

With the new syntax of RxJS 5.5+, this becomes as the following:

// RxJS 6
import { EMPTY, empty, of } from "rxjs";

// rxjs 5.5+ (<6)
import { empty } from "rxjs/observable/empty";
import { of } from "rxjs/observable/of";

empty(); // deprecated use EMPTY
EMPTY;
of({});

Just one thing to keep in mind, EMPTY completes the observable, so it won't trigger next in your stream, but only completes. So if you have, for instance, tap, they might not get trigger as you wish (see an example below).

Whereas of({}) creates an Observable and emits next with a value of {} and then it completes the Observable.

E.g.:

EMPTY.pipe(
    tap(() => console.warn("i will not reach here, as i am complete"))
).subscribe();

of({}).pipe(
    tap(() => console.warn("i will reach here and complete"))
).subscribe();

RxJS6 (without compatibility package installed)

There's now an EMPTY constant and an empty function.

  import { Observable, empty, EMPTY, of } from 'rxjs';

  //This is now deprecated
  var delay = empty().pipe(delay(1000));     
  var delay2 = EMPTY.pipe(delay(1000));

Observable.empty() doesn't exist anymore.

In my case with Angular2 and rxjs, it worked with:

import {EmptyObservable} from 'rxjs/observable/EmptyObservable';
...
return new EmptyObservable();
...

Several ways to create an Empty Observable:

They just differ on how you are going to use it further (what events it will emit after: next, complete or do nothing) e.g.:

• Observable.never() - emits no events and never ends.
• Observable.empty() - emits only complete.
• Observable.of({}) - emits both next and complete (Empty object literal passed as an example).

Use it on your exact needs)

Yes, there is am Empty operator

Rx.Observable.empty();

For typescript, you can use from:

Rx.Observable<Response>.from([])