skipUntil

Returns an Observable that skips items emitted by the source Observable until a second Observable emits an item.

skipUntil<T>(notifier: Observable<any>): MonoTypeOperatorFunction<T>

Parameters

Returns

MonoTypeOperatorFunction<T>: A function that returns an Observable that skips items from the source Observable until the second Observable emits an item, then emits the remaining items.

Description

The skipUntil operator causes the observable stream to skip the emission of values ​​until the passed in observable emits the first value. This can be particularly useful in combination with user interactions, responses of http requests or waiting for specific times to pass by.

Internally the skipUntil operator subscribes to the passed in observable (in the following called notifier) in order to recognize the emission of its first value. When this happens, the operator unsubscribes from the notifier and starts emitting the values of the source observable. It will never let the source observable emit any values if the notifier completes or throws an error without emitting a value before.

Example

In the following example, all emitted values ​​of the interval observable are skipped until the user clicks anywhere within the page.

import { interval, fromEvent } from 'rxjs';
import { skipUntil } from 'rxjs/operators';

const intervalObservable = interval(1000);
const click = fromEvent(document, 'click');

const emitAfterClick = intervalObservable.pipe(
  skipUntil(click)
);
// clicked at 4.6s. output: 5...6...7...8........ or
// clicked at 7.3s. output: 8...9...10..11.......
const subscribe = emitAfterClick.subscribe(value => console.log(value));