API / rxjs/operators

window

Branch out the source Observable values as a nested Observable whenever windowBoundaries emits.

window<T>(windowBoundaries: Observable<any>): OperatorFunction<T, Observable<T>>

Parameters

windowBoundaries

An Observable that completes the previous window and starts a new window.

Returns

OperatorFunction<T, Observable<T>>: An Observable of windows, which are Observables emitting values of the source Observable.

Description

It's like buffer, but emits a nested Observable instead of an array.

Returns an Observable that emits windows of items it collects from the source Observable. The output Observable emits connected, non-overlapping windows. It emits the current window and opens a new one whenever the Observable windowBoundaries emits an item. Because each window is an Observable, the output is a higher-order Observable.

Example

In every window of 1 second each, emit at most 2 click events

import { fromEvent, interval } from 'rxjs'; import { window, mergeAll, map take } from 'rxjs/operators'; const clicks = fromEvent(document, 'click'); const sec = interval(1000); const result = clicks.pipe( window(sec), map(win => win.pipe(take(2))), // each window has at most 2 emissions mergeAll(), // flatten the Observable-of-Observables ); result.subscribe(x => console.log(x));

See Also