How to stop an interval on an Observable in RxJS

Question

I have a specific situation where I'm using an RxJS interval, but at any given moment I may need to stop that interval. I assumed there was something easy like a cancel() or stop(). Similar to clearTimeout. This is possible to stop an interval once it's going? If not, what would be another approach.

Basically I have a large array that I'm stepping through. But there are external things that could happen that make it necessary to stop that step through and continue on to a new task. I'm hoping it's something simple that I'm just missing in the docs. Thanks

Possible duplicate, answered [here](https://stackoverflow.com/questions/41070443/rxjava-how-to-stop-and-resume-a-hot-observable-interval) — udalmik, Oct 26 '17 at 21:00

score 48 · Answer 1 · answered Oct 26 '17 at 20:50

48

This is possible to stop an interval once it's going?

You can use the .takeUntil operator to complete an observable when some other observable emits. You'll of course need to set that other observable up to emit values in a way that is useful to you, but here's an example that stops an interval after 5 seconds:

Rx.Observable.interval(100)
  .takeUntil(Rx.Observable.timer(5000))
  .subscribe(val => console.log(val));

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/5.5.2/Rx.min.js"></script>

answered Oct 26 '17 at 20:50

Nicholas Tower

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Thanks, I ended up using **takeWhile** `Observable.interval( 100 ).takeWhile( val => takeUntil ).subscribe( val => { ...` – Phil Huhn Apr 23 '18 at 16:16
Isn't this creating a timer multiple number of times which is bad ?. The solution by @P.Huhn takes care of that i think or not ? – user2599052 Jan 08 '21 at 06:35
I am trying check if something is done, but after n tries give up. – Phil Huhn Jan 10 '21 at 22:34

martin · Answer 2 · 2019-07-24T13:39:52.603

45

Just unsubscribe:

import { interval } from 'rxjs';

const subscription = interval(1000)
  .pipe(...)
  .subscribe();

...

subscription.unsubscribe();

Note that since interval() is asynchronous you can call unsubscribe() inside the subscribe's callback as well.

Jul 2019: Updated for RxJS 6.

edited Jul 24 '19 at 13:39

answered Oct 26 '17 at 20:52

martin

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`subscribe` leads to imperative reactive code, particularly when the intent is to `unsubscribe`. This is easier to construct at small scales, but harder to maintain at large scales. E.g. https://medium.com/@benlesh/rxjs-dont-unsubscribe-6753ed4fda87 recommends avoiding this. – ariels May 13 '18 at 13:51
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I took the liberty of creating a [jsfiddle](https://jsfiddle.net/anied/ruzqty4k/8/) where you can see this solution in action. – Alexander Nied Sep 30 '19 at 14:29

How to stop an interval on an Observable in RxJS

2 Answers2