delay

signature: delay(delay: number | Date, scheduler: Scheduler): Observable

Delay emitted values by given time.

Ultimate RxJS

Examples

Example 1: Delay to recognize long press

( StackBlitz )

import { fromEvent, of } from 'rxjs';
import { mergeMap, delay, takeUntil } from 'rxjs/operators';
const mousedown$ = fromEvent(document, 'mousedown');
const mouseup$ = fromEvent(document, 'mouseup');
mousedown$
.pipe(
mergeMap(event =>
of(event).pipe(
delay(700),
takeUntil(mouseup$)
)
)
)
.subscribe(event => console.log('Long Press!', event));

Example 2: Delay for increasing durations

( StackBlitz )

// RxJS v6+
import { of, merge } from 'rxjs';
import { mapTo, delay } from 'rxjs/operators';
//emit one item
const example = of(null);
//delay output of each by an extra second
const message = merge(
example.pipe(mapTo('Hello')),
example.pipe(
mapTo('World!'),
delay(1000)
),
example.pipe(
mapTo('Goodbye'),
delay(2000)
),
example.pipe(
mapTo('World!'),
delay(3000)
)
);
//output: 'Hello'...'World!'...'Goodbye'...'World!'
const subscribe = message.subscribe(val => console.log(val));

Additional Resources

📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/delay.ts