RXJS 5 .subscribe() without arguments

问题

So a quick question. I've been using RxJS 5 for a few months now, and I've run into a bit of behavior that I don't really understand, as I haven't been able to look it up anywhere.

I'm in a situation where subscribing to an observable chain with simply .subscribe(); doesn't trigger the observable.

However, if I add an onNext callback (empty or not), the observable triggers, and the chain processes: .subscribe(() => {});

Can anyone explain why this behavior happens?

EDIT2 - Removed irrelevant example

回答1:

.subscribe() actually doesn't require any parameters, it will just create an emptyObserver if none are given, which should work just as well.

It is possible though, that there are issues related to this in some of the 5.0.0-beta versions - in case you are using one of those versions, you should update to a more stable release.

const obs$ = Rx.Observable.of("Foo")
  .do(() => console.log("triggered!"));
  
obs$.subscribe();
obs$.subscribe();

<script src="https://unpkg.com/rxjs@5.1.1/bundles/Rx.min.js"></script>

回答2:

Thanks to Damian Hercun for informing that this was a now-fixed bug in RxJS 5.4.2.

Info:

https://github.com/ReactiveX/rxjs/pull/1935

https://github.com/ReactiveX/rxjs/issues/1921

来源：https://stackoverflow.com/questions/42333187/rxjs-5-subscribe-without-arguments