Be aware about the BehaviorObservable.toPromise() not work as expected.

[huan]

We will expect it resolve immediately but it doesn't.

See: https://github.com/Reactive-Extensions/RxJS/issues/1088 - BehaviourSubject toPromise isn't working

UPDATE:

• Observable.toPromise and Observable.last().subscribe are identical

return new Promise((resolve, reject) => {
    let value;
    this.subscribe((x) => value = x, (err) => reject(err), () => resolve(value));
});

[huan]

SOLUTION:

await behaviorSubject.asObservable.first().toPromise()

The magic resides in the above first() which will make it work as expected.

[ErraticFox]

UPDATE: for anyone else viewing this later the solution would be:

await behaviorSubject.pipe(take(1)).toPromise()

[huan]

@ErraticFox Thanks! We are in the stage of RxJS 6 now! 🎉

[PabloPerezAguilo]

UPDATE: for anyone else viewing this later the solution would be:

await behaviorSubject.pipe(take(1)).toPromise()

Works! Thx! Not all hero wear capes.

[ErraticFox]

@PabloPerezAguilo just make sure to pay the good deed forward. :)