How can I emit values with delay in RXJS?

Question

I have an array of values [1,2,3] .

I want to emit each value with delay

I've managed to do it with the zip operator :

 Rx.Observable.from([1,2,3])
   .zip(Rx.Observable.timer(0, 1000), x => x)
   .subscribe((e) => console.log(e));

Question:

Is there any more appropriate operator for such task ? Involving an inner observable seems ( to me) incorrect approach.
Should I unsubscribe the inner Observable manually ? Becuase basically no one tells it to stop.

jsbin

Answer 1

You can delay each emission itself and wait until the previous one completed. Like this for example:

Rx.Observable.from([1,2,3])
   .concatMap(x => Observable.of(x).delay(1000)) // or Observable.timer(1000).mapTo(x)
   .subscribe((e) => console.log(e));

If you want to use zip you don't need to unsubscribe the timer but you need to tell it to complete (for example with take() or takeUntil()).