Angular2, unsubsribe from event in ngOnDestroy [duplicate]

Answer 1

You get a subscription from .subscribe(). Use its unsubscribe() method to cancel the subscription.

@Component({
  selector: 'receiver',
  template: `Count: {{count}}`,
})
export class ReceiverComponent {
  public count = 0;
  private subscription;
  constructor(private eventService:EventService) {
    this.subscription = this.eventService.myEvent.subscribe(() => this.count++;);
  }
  ngOnDestroy() {
    this.subscription.unsubscribe();
  }
}

See also

• how to unsubscribe several subscriber in angular 2

• timer.unsubscribe is not a function Angular2

Answer 2

I think your should cancel the subscription, as described below:

export class ReceiverComponent {
  public count = 0;
  private id;

  constructor(private eventService:EventService) {
    this.id = Date.now();
    console.log("ReceiverComponent constructor " + this.id);
    this.subscription = this.eventService.myEvent.subscribe(() => {
      console.log("count " + this.count + " (id ReceiverComponent instance: " + this.id + ")");
      this.count++;
    });
  }

  ngOnDestroy() {
    console.log("onDestroy of ReceiverComponent " + this.id)
    //this cause "Cannot subscribe to a disposed Subject."
    //this.eventService.myEvent.unsubscribe();
    this.subscription.unsubscribe();
  }
}

In fact, EventEmitters are shared observables, i.e. hot observables. Here is a link that could interest you: https://github.com/Reactive-Extensions/RxJS/blob/master/doc/gettingstarted/creating.md.

Hope it helps you, Thierry