sample

Emits the most recently emitted value from the source Observable whenever another Observable, the notifier, emits.

It's like sampleTime, but samples whenever the notifier ObservableInput emits something.

Whenever the notifier ObservableInput emits a value, sample looks at the source Observable and emits whichever value it has most recently emitted since the previous sampling, unless the source has not emitted anything since the previous sampling. The notifier is subscribed to as soon as the output Observable is subscribed.

Example

On every click, sample the most recent seconds timer

import { fromEvent, interval, sample } from 'rxjs';

const seconds = interval(1000);
const clicks = fromEvent(document, 'click');
const result = seconds.pipe(sample(clicks));

result.subscribe(x => console.log(x));