p-debounce

What is p-debounce?

The p-debounce npm package is a utility for debouncing promise-returning and async functions. Debouncing is a technique used to limit the rate at which a function can fire. It ensures that the function is only called once after a specified delay has elapsed since the last time it was invoked.

What are p-debounce's main functionalities?

Basic Debouncing

This feature allows you to debounce an async function. The function will only be called once after the specified delay (200ms in this case) has elapsed since the last invocation.

const pDebounce = require('p-debounce');

const expensiveFunction = async input => {
  console.log('Processing:', input);
  return input;
};

const debouncedFunction = pDebounce(expensiveFunction, 200);

debouncedFunction('first call');
debouncedFunction('second call');
// Only 'second call' will be processed after 200ms

Debouncing with Leading Edge

This feature allows you to debounce an async function with the option to trigger the function on the leading edge of the delay period. This means the function will be called immediately on the first invocation and then debounced for subsequent calls.

const pDebounce = require('p-debounce');

const expensiveFunction = async input => {
  console.log('Processing:', input);
  return input;
};

const debouncedFunction = pDebounce(expensiveFunction, 200, {leading: true});

debouncedFunction('first call');
debouncedFunction('second call');
// 'first call' will be processed immediately, 'second call' will be ignored if it occurs within 200ms

Other packages similar to p-debounce

lodash.debounce

lodash.debounce is a popular utility from the Lodash library that provides similar debouncing functionality. It is widely used and well-documented, but it does not natively support promise-returning or async functions like p-debounce does.

debounce

debounce is a lightweight npm package that provides basic debouncing functionality. It is simple and easy to use but lacks the advanced features and async support that p-debounce offers.

throttle-debounce

throttle-debounce is a package that provides both throttling and debouncing utilities. It is versatile and can be used for various rate-limiting scenarios, but it does not specifically cater to promise-returning or async functions like p-debounce.

README

p-debounce

Debounce promise-returning & async functions

Install

$ npm install p-debounce

Usage

import pDebounce from 'p-debounce';

const expensiveCall = async input => input;

const debouncedFn = pDebounce(expensiveCall, 200);

for (const number of [1, 2, 3]) {
	console.log(await debouncedFn(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.

pDebounce.promise(function_)

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.

function_

Type: Function

Promise-returning/async function to debounce.

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

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

const debouncedFn = pDebounce.promise(expensiveCall);

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

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…