What does takeUntil() do?

AngularJunior~1 min read

takeUntil() is an RxJS operator that automatically completes a subscription when another stream fires.

In simple terms:

You're saying: "Listen to this stream until this other event happens."

Example:

private destroy$ = new Subject<void>();

this.myStream$
  .pipe(takeUntil(this.destroy$))
  .subscribe(value => {
    console.log(value);
  });

// When the component is destroyed:
this.destroy$.next(); // stops the subscription
this.destroy$.complete();

This is handy in Angular for unsubscribing automatically in ngOnDestroy().

Without `takeUntil()`:

You'd have to store the subscription and manually call unsubscribe().

With takeUntil(), everything happens through the stream: reactive and safe.

Where it's used:

In Angular components
When working with interval(), valueChanges, router.events, and other infinite streams

Conclusion:

takeUntil() = a way of saying: "The subscription should stay alive until a stop signal arrives."

No leaks, everything under control.

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What does takeUntil() do?

#In simple terms:

#Example:

#Without takeUntil():

#Where it's used:

#Conclusion: