Empty subscribe on valueChanges in Angular2

问题

I have this weird case, a subscribe that never fires if left empty.

This doesn't work:

this.formGroup.get('unitCount').valueChanges
.do(value => console.log(value))
.subscribe();

When this works fine:

this.formGroup.get('unitCount').valueChanges
.do(value => console.log(value))
.subscribe(() => true);

Here I used () => true, but it could anything, false, void 0, even an empty object {}

Why can't I leave the subscribe() empty?

回答1:

You probably have a older version of RxJS 5. This was a bug but is already fixed.

I can't find since what version it works correctly, but this PR could be related to this: https://github.com/ReactiveX/rxjs/pull/1935

Otherwise, show what exact RxJS version you're using.

来源：https://stackoverflow.com/questions/45608374/empty-subscribe-on-valuechanges-in-angular2