debounce

What is debounce?

The debounce npm package provides a function that delays the execution of a function until after a specified wait time has elapsed since the last time it was invoked. This is particularly useful for rate-limiting the execution of functions that may be called frequently, such as during window resizing, scrolling, or keyboard input, to improve performance and reduce the number of unnecessary function calls.

What are debounce's main functionalities?

Debouncing function calls

This code sample demonstrates how to use the debounce package to debounce a function that logs 'Input saved!' to the console. The function will only be called after 250 milliseconds have passed without the 'input' event being triggered.

const debounce = require('debounce');
const saveInput = debounce(() => console.log('Input saved!'), 250);
window.addEventListener('input', saveInput);

Immediate invocation option

This code sample shows how to use the debounce package with the immediate flag set to true. This causes the function to be executed immediately on the first call, then debounced for subsequent calls within the 250-millisecond timeframe.

const debounce = require('debounce');
const processChange = debounce(() => console.log('Change processed!'), 250, true);
window.addEventListener('change', processChange);

Canceling a debounced call

This code sample illustrates how to cancel a debounced function call. The 'cancel' method is used to prevent the debounced function from being called if it has not yet been executed.

const debounce = require('debounce');
const expensiveOperation = debounce(() => console.log('Operation executed!'), 1000);
expensiveOperation();
expensiveOperation.cancel();

Other packages similar to debounce

lodash.debounce

lodash.debounce is a function from the popular Lodash library that provides debouncing capabilities. It is similar to debounce but comes with additional options for leading and trailing invocation, and maxWait time. Lodash's debounce is often preferred for its extended functionality and reliability within the Lodash ecosystem.

throttle-debounce

throttle-debounce is a package that offers both throttle and debounce functions. While debounce delays function execution, throttle ensures that a function is only called at most once in a specified period. This package is useful for those who need both functionalities and prefer a combined solution.

p-debounce

p-debounce is a package that provides debouncing functionality for promises. It is similar to debounce but is specifically designed to work with functions that return promises, ensuring that a promise-returning function is not invoked too frequently.

README

debounce

Delay function calls until a set time elapses after the last invocation

Install

npm install debounce

Usage

import debounce from 'debounce';

function resize() {
	console.log('height', window.innerHeight);
	console.log('width', window.innerWidth);
}

window.onresize = debounce(resize, 200);

(You can also use const debounce = require('debounce'))

To check if the debounce delay is currently active:

window.onresize.isPending;

To later clear the timer and cancel currently scheduled executions:

window.onresize.clear();

To execute immediately only if you have scheduled invocations and reset the timer:

window.onresize.flush();

To execute immediately and reset the timer if it was previously set:

window.onresize.trigger();

API

debounce(fn, wait, options?)

Creates a debounced function that delays execution until wait milliseconds have passed since its last invocation.

Set the immediate option to true to execute the function immediately at the start of the wait interval, preventing issues such as double-clicks on a button.

The returned function has the following methods:

• .isPending indicates whether the debounce delay is currently active.
• .clear() cancels any scheduled executions.
• .flush() if an execution is scheduled then it will be immediately executed and the timer will be cleared.
• .trigger() executes the function immediately and clears the timer if it was previously set.

Related

• p-debounce - Similar but handles promises
• throttleit - Throttle a function to limit its execution rate