Will takeUntil() work with Observable<void>?

Question

The documentation says that takeUntil continues to emit values until the passed observable emits a value . It doesn't say until subscribe is called.

I'm wondering if the following is safe to do?

const x = new Subject<void>();

async.pipe(takeUntil(x)).subscribe(()=>.....);

x.next(); // <-- no value

The alternative would be to emit some kind of value in x.next(true) .

Answer 1

Yes calling x.next() is safe. By inspecting the source code it can be seen that takeUntil does not use the value emitted from Observable x and simply calls complete() on the source Observable.