[SO] Why RxJS startWIth does not emit when used with lastValueFrom?

[vajahath]

SO Question

Short summary:

Why this thing does not resolve at all?

const obs = new Subject().asObservable().pipe(startWith('startWith'));
lastValueFrom(obs).then(console.log);

[demensky]

lastValueFrom:

Converts an observable to a promise by subscribing to the observable, waiting for it to complete…

In your case "complete" never happens.

Here is an example where console.log will be executed:

const sub = new Subject();
const obs = sub.asObservable().pipe(startWith('startWith'));
lastValueFrom(obs).then(console.log);

sub.complete();