Stop next execution of Rxjs observer?

Question

I am trying with the basic use case of a Rxjs observer. This is what I am doing:

const { Observable } = require('rxjs');

Observable.create(o => { 
  setTimeout(() => o.next('hi'), 1000); 
  setTimeout(() => { throw new Error('A mistake') }, 1500); 
  setTimeout(() => o.next('this should not print'), 2000) }
).subscribe({
  next: x => console.log(x),
  error: y => console.log('error', y),
  complete: () => console.log('done')
});

The out put of this is the following:

> hi
Error: A mistake
    at Timeout.setTimeout [as _onTimeout] (repl:1:89)
    at ontimeout (timers.js:498:11)
    at tryOnTimeout (timers.js:323:5)
    at Timer.listOnTimeout (timers.js:290:5)
> this should not print

What I need to do is stop the execution of the next, and even If I unsubscribe my subscription it is not stopping the next execution.

I tried like this too:

let subscription;

let source = Observable.create(o => { 
  try {
    setTimeout(() => o.next('hi'), 1000); 
    setTimeout(() => { throw new Error('A mistake') }, 1500); 
    setTimeout(() => o.next('this should not print'), 2000) 
  } catch (e) {
    subscription.unsubscribe();
    return 'error';
  }
});
subscription = source.subscribe({
  next: x => console.log(x),
  error: y => console.log('error', y),
  complete: () => console.log('done')
});

but no chance... it did not stop.

What I have as code is not just set timeout I have async and await code like this:

let subscription;

let source = Observable.create(async o => { 
  try {
    o.next(await anEvent()); 
    o.next(await anEventThatThrowsAnException()); 
    o.next(await anEventThatIWantToAvoidDueToTheException()); 
  } catch (e) {
    subscription.unsubscribe();
    return 'error';
  }
});
subscription = source.subscribe({
  next: x => console.log(x),
  error: y => console.log('error', y),
  complete: () => console.log('done')
});

How can I achieve this code to stop the "this should not print" ?

Answer 1

After you set the timer with setTimeout , you will not prevent it's execution with unsubscribe .

You will need to manually clear your timeouts.

Note that you can save your timeouts in variables var myTimeout = setTimeout(f,ms); then you can cancel then clearTimeout(myTimeout);

Read More:

• setTimeout

• clearTimeout

Answer 2

This is the way to make it work with observer.error as stated by ABOS. In fact this is his example and it works.

So Just for documentation purposes I answered this question with his answer from the comment.

ABOS answer

I just thought that if someone is having problem trying to handle errors throwing the error instead of catching and executing observer.error in the way that is needed.