debounce

signature: debounce(durationSelector: function): Observable

Discard emitted values that take less than the specified time, based on selector function, between output.


:bulb: Though not as widely used as debounceTime, debounce is important when the debounce rate is variable!


Examples

Example 1: Debounce on timer

( jsBin | jsFiddle )

import { of } from 'rxjs/observable/of';
import { timer } from 'rxjs/observable/timer';
import { debounce } from 'rxjs/operators';

//emit four strings
const example = of('WAIT', 'ONE', 'SECOND', 'Last will display');
/*
    Only emit values after a second has passed between the last emission,
    throw away all other values
*/
const debouncedExample = example.pipe(debounce(() => timer(1000)));
/*
    In this example, all values but the last will be omitted
    output: 'Last will display'
*/
const subscribe = debouncedExample.subscribe(val => console.log(val));
Example 2: Debounce at increasing interval

( jsBin | jsFiddle )

import { interval } from 'rxjs/observable/interval';
import { timer } from 'rxjs/observable/timer';
import { debounce } from 'rxjs/operators';

//emit value every 1 second, ex. 0...1...2
const interval = interval(1000);
//raise the debounce time by 200ms each second
const debouncedInterval = interval.pipe(debounce(val => timer(val * 200)));
/*
  After 5 seconds, debounce time will be greater than interval time,
  all future values will be thrown away
  output: 0...1...2...3...4......(debounce time over 1s, no values emitted)
*/
const subscribe = debouncedInterval.subscribe(val =>
  console.log(`Example Two: ${val}`)
);

Additional Resources


:file_folder: Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/patching/operator/debounce.ts

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