Do I need to `complete()` takeUntil Subject inside ngOnDestroy?

Question

To avoid Observable memory leaks inside Components, I am using takeUntil() operator before subscribing to Observable.

I write something like this inside

Answer 1

You only need to unsubscribe like:

subscr: Subscription;

ngOnInit() {
  this.subscr = this.http
    .get('test')
    .pipe(takeUntil(this.unsubscribe$))
    .subscribe(x => console.log(x));
}

ngOnDestroy() {
  this.subscr.unsubscribe();
}

To unsubscribe using takeUntil():

The solution is to compose our subscriptions with the takeUntil operator and use a subject that emits a truthy value in the ngOnDestroy:

export class AppComponent implements OnInit, OnDestroy {
  destroy$: Subject = new Subject();

  ngOnInit() {
   this.http
    .get('test')
    .pipe(takeUntil(this.unsubscribe$))
    .subscribe(x => console.log(x));
  }

  ngOnDestroy() {
    this.destroy$.next(true);
  }
}

Note that using an operator like takeUntil instead of manually unsubscribing will also complete the observable, triggering any completion event on the observable.

See here