What is the difference between subscription.unsubscribe() and subscription.remove()?

I am using Angular 5 and have subscribed an observable using the subscribe() method. I want to know if only calling the unsubscribe() method on the subscription will be sufficient to cleanup everything, or should I also call remove() method?

code snippet:

`

// somewhere in a method
this.s1 = someObservable.subscribe((value) => {
     //somecode
 });
// in ngOnDestroy
this.s1.unsubscribe(); // should I also call .remove()

`

Answer

.remove remove the subscription from an internal list, but it does not unsubscribe.

.unsubscribe clean up everything, do the unsubscribe and remove the observer from the internal list. (There was a bug (fixed) that didn’t remove the observer from the list)

.takeWhile keep alive the subscription whilst a certain situation continues to be false

example:

this.service.method()
.subscribe(res => {
  //logic
});

this will never unsubscribe.

this.service.method()
    takeWhile(() => this.isAlive) // <-- custom variable setted to true
    .subscribe(res => {
      //logic
    });

ngOnDestroy(){
    this.isAlive = false;
}

Automatic unsubscribe when the component is going to be destroyed.

   this.s1 = someObservable.subscribe((value) => {
        //somecode
    });

public yourMethod(){
    this.s1.unsubscribe();
}

this subscription will exists and be “alive” until yourFunction is not called.

—

I personally like to use the rxjs operator takeWhile to keep the code clean. In a very big project or single component having multiple subscription it’s confusing having (IE) 30 variables: Subscription. So If you are asking when to use the takeWhile operator my answer is: (Taking as example one subscription) -> If you are sure that the unsubscribe needs to be done when the component is destroyed, use takeWhile. If you need to unsubscribe in a certain scenario where the component is still “alive”, use the second example I wrote.

Hope to have clarified the argument.