debounceTime

function stable

Emits a notification from the source Observable only after a particular time span has passed without another source emission.

`debounceTime<T>(dueTime: number, scheduler: SchedulerLike = asyncScheduler): MonoTypeOperatorFunction<T>`

Parameters

dueTime

The timeout duration in milliseconds (or the time unit determined internally by the optional scheduler) for the window of time required to wait for emission silence before emitting the most recent source value.

scheduler

Optional. Default is asyncScheduler.

The SchedulerLike to use for managing the timers that handle the timeout for each value.

Returns

MonoTypeOperatorFunction<T>: A function that returns an Observable that delays the emissions of the source Observable by the specified dueTime, and may drop some values if they occur too frequently.

Description

It's like delay, but passes only the most recent notification from each burst of emissions.

debounceTime marble diagram

debounceTime delays notifications emitted by the source Observable, but drops previous pending delayed emissions if a new notification arrives on the source Observable. This operator keeps track of the most recent notification from the source Observable, and emits that only when dueTime has passed without any other notification appearing on the source Observable. If a new value appears before dueTime silence occurs, the previous notification will be dropped and will not be emitted and a new dueTime is scheduled. If the completing event happens during dueTime the last cached notification is emitted before the completion event is forwarded to the output observable. If the error event happens during dueTime or after it only the error event is forwarded to the output observable. The cache notification is not emitted in this case.

This is a rate-limiting operator, because it is impossible for more than one notification to be emitted in any time window of duration dueTime, but it is also a delay-like operator since output emissions do not occur at the same time as they did on the source Observable. Optionally takes a SchedulerLike for managing timers.

Example

Emit the most recent click after a burst of clicks

import { fromEvent } from 'rxjs';
import { debounceTime } from 'rxjs/operators';

const clicks = fromEvent(document, 'click');
const result = clicks.pipe(debounceTime(1000));
result.subscribe(x => console.log(x));