p-debounce

Debounce promise-returning & async functions

Install

npm install p-debounce

Usage

import pDebounce from 'p-debounce';

const expensiveCall = async input => input;

const debouncedFunction = pDebounce(expensiveCall, 200);

for (const number of [1, 2, 3]) {
	(async () => {
		console.log(await debouncedFunction(number));
	})();
}
//=> 3
//=> 3
//=> 3

API

pDebounce(fn, wait, options?)

Returns a function that delays calling fn until after wait milliseconds have elapsed since the last time it was called.

fn

Type: Function

Promise-returning/async function to debounce.

wait

Type: number

Milliseconds to wait before calling fn.

options

Type: object

before

Type: boolean
Default: false

Call the fn on the leading edge of the timeout. Meaning immediately, instead of waiting for wait milliseconds.

signal

Type: AbortSignal

An AbortSignal to cancel the debounced function.

pDebounce.promise(function_, options?)

Execute function_ unless a previous call is still pending, in which case, return the pending promise. Useful, for example, to avoid processing extra button clicks if the previous one is not complete.

import {setTimeout as delay} from 'timers/promises';
import pDebounce from 'p-debounce';

const expensiveCall = async value => {
	await delay(200);
	return value;
};

const debouncedFunction = pDebounce.promise(expensiveCall);

for (const number of [1, 2, 3]) {
	(async () => {
		console.log(await debouncedFunction(number));
	})();
}
//=> 1
//=> 1
//=> 1

function_

Type: Function

Promise-returning/async function to debounce.

options

Type: object

after

Type: boolean
Default: false

If a call is made while a previous call is still running, queue the latest arguments and run the function again after the current execution completes.

Use cases:

• With after: false (default): API fetches, data loading, read operations - concurrent calls share the same result.
• With after: true: Saving data, file writes, state updates - ensures latest data is never lost.

import {setTimeout as delay} from 'timers/promises';
import pDebounce from 'p-debounce';

const save = async data => {
	await delay(200);
	console.log(`Saved: ${data}`);
	return data;
};

const debouncedSave = pDebounce.promise(save, {after: true});

// If data changes while saving, it will save again with the latest data
debouncedSave('data1');
debouncedSave('data2'); // This will run after the first save completes
//=> Saved: data1
//=> Saved: data2

Related

• p-throttle - Throttle promise-returning & async functions
• p-limit - Run multiple promise-returning & async functions with limited concurrency
• p-memoize - Memoize promise-returning & async functions
• debounce-fn - Debounce a function
• More…