Argthtjtr

Is it a good practice to call the complete() method for each Output() EventEmitter in my angular component's ngOnDestroy callback?
That way any subscription made to those outputs would end straight when the component is destroyed. And in most cases, I would not have to worry about unsubscribing anymore in parent components. What do you think?

Example

I have a parent component that subscribes to an output event of a child component.
I usally do:

childCompoment.event.pipe(

    takeUntil(this.parentComponentDestroyed$), // end subscription when parent is destroyed

  ).subscribe((eventData: any) => {

    // do stuff

  });

}

Now if the child component gets destroyed, that does not end my parent subscription automatically. I have to wait until the parent component is destroyed itself.
If i call event.complete() in the child components' OnDestroy callback then my subscription will end as soon the child component is destroyed.
What is the best approach in that case?

Well, I personally feel that it's not really necessary to call complete() on the @Output EventEmitter. I'm saying that because it's up to us to call emit from the Child Component.

It's similar to not calling unsubscribe on an Observable Subscription that is returned from HttpClient in cases it's just called once.

Here's an amazingly enlightening article by Ben Lesh who's Rxjs lead. Reading this article will make it clear of when to unsubscribe and when not to.

You can think about the idea of calling complete() on similar lines.

UPDATE:

The example added by you exhibits an extremely rare use-case when the ChildComponent was used inside the Parent Component Typescript class, probably using ViewChild and it's events were listened to in the Parent Component. In this particular scenario, I think it would be important to unsubscribe in ngOnDestroy.

But in most of the cases, the Child Component's @Output events are generally listened to by a handler in the Parent Component. And the events fired from a Child Component are generally in our hands. And if the Child Component is destroyed, then it won't really fire any events, so I don't really think there's a need to explicitly call complete or unsubscribe in ngOnDestroy.