delay.tsā¢2.29 kB
import { asyncScheduler } from '../scheduler/async';
import { MonoTypeOperatorFunction, SchedulerLike } from '../types';
import { delayWhen } from './delayWhen';
import { timer } from '../observable/timer';
/**
* Delays the emission of items from the source Observable by a given timeout or
* until a given Date.
*
* <span class="informal">Time shifts each item by some specified amount of
* milliseconds.</span>
*
* 
*
* If the delay argument is a Number, this operator time shifts the source
* Observable by that amount of time expressed in milliseconds. The relative
* time intervals between the values are preserved.
*
* If the delay argument is a Date, this operator time shifts the start of the
* Observable execution until the given date occurs.
*
* ## Examples
*
* Delay each click by one second
*
* ```ts
* import { fromEvent, delay } from 'rxjs';
*
* const clicks = fromEvent(document, 'click');
* const delayedClicks = clicks.pipe(delay(1000)); // each click emitted after 1 second
* delayedClicks.subscribe(x => console.log(x));
* ```
*
* Delay all clicks until a future date happens
*
* ```ts
* import { fromEvent, delay } from 'rxjs';
*
* const clicks = fromEvent(document, 'click');
* const date = new Date('March 15, 2050 12:00:00'); // in the future
* const delayedClicks = clicks.pipe(delay(date)); // click emitted only after that date
* delayedClicks.subscribe(x => console.log(x));
* ```
*
* @see {@link delayWhen}
* @see {@link throttle}
* @see {@link throttleTime}
* @see {@link debounce}
* @see {@link debounceTime}
* @see {@link sample}
* @see {@link sampleTime}
* @see {@link audit}
* @see {@link auditTime}
*
* @param due The delay duration in milliseconds (a `number`) or a `Date` until
* which the emission of the source items is delayed.
* @param scheduler The {@link SchedulerLike} to use for managing the timers
* that handle the time-shift for each item.
* @return A function that returns an Observable that delays the emissions of
* the source Observable by the specified timeout or Date.
*/
export function delay<T>(due: number | Date, scheduler: SchedulerLike = asyncScheduler): MonoTypeOperatorFunction<T> {
const duration = timer(due, scheduler);
return delayWhen(() => duration);
}