How to unsubscribe from an Observable returned by forkJoin?

Question

In my Angular2-typescript app, I\'m using forkJoin to return an Observable only once all the parallel HTTP calls were made.

Issue: the subscription call

Answer 1

As forkJoin reference says, it

Runs all observable sequences in parallel and collect their last elements.

This means that the operator gets values from completed observables and returns a completed observable with single value. There's no need to unsubscribe from it.

Answer 2

You can cancel it. Let's say observables is an array of http requests you prepared to trigger (executed via httpClient).

this.forkJoinSubscription = forkJoin(observables).subscribe(responses => {
    . . . do something
});

this.forkJoinSubscription.unsubscribe();

You may notice in your network tab that those requests were cancelled.