About

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. It includes many web standards from WHATWG DOM and HTML.

The goal of Happy DOM is to emulate enough of a web browser to be useful for testing, scraping web sites and server-side rendering.

Happy DOM focuses heavily on performance and can be used as an alternative to JSDOM.

DOM Features

• Custom Elements (Web Components)

• Shadow Root (Shadow DOM)

• Declarative Shadow DOM

• Mutation Observer

• Tree Walker

• Fetch

And much more..

Works With

• Google LitHTML

• Google LitElement

• React

• Angular

• Vue

Module Systems

• ESM
• CommonJS

Installation

npm install happy-dom

Usage

Happy DOM can be used as a simulated Browser or by using the Window class directly to quickly setup up a DOM.

Window

import { Window } from 'happy-dom';

const window = new Window({ url: 'https://localhost:8080' });
const document = window.document;

document.body.innerHTML = '<div class="container"></div>';

const container = document.querySelector('.container');
const button = document.createElement('button');

container.appendChild(button);

// Outputs "<div class="container"><button></button></div>"
console.log(document.body.innerHTML);

Browser

import { Browser, BrowserErrorCaptureEnum } from 'happy-dom';

const browser = new Browser({ settings: { errorCapture: BrowserErrorCaptureEnum.processLevel } });
const page = browser.newPage();

// Navigates page
await page.goto('https://github.com/capricorn86');

// Clicks on link
page.mainFrame.document.querySelector('a[href*="capricorn86/happy-dom"]').click();

// Waits for all operations on the page to complete (fetch, timers etc.)
await page.waitUntilComplete();

// Outputs "GitHub - capricorn86/happy-dom: Happy DOM..."
console.log(page.mainFrame.document.title);

// Closes the browser
await browser.close();

Documentation

Read more about how to use Happy DOM in our Wiki.

Performance

| Operation | JSDOM | Happy DOM | | ------------------------------------ | ------- | --------- | | Import / Require | 333 ms | 45 ms | | Parse HTML | 256 ms | 26 ms | | Serialize HTML | 65 ms | 8 ms | | Render custom element | 214 ms | 19 ms | | querySelectorAll('tagname') | 4.9 ms | 0.7 ms | | querySelectorAll('.class') | 6.4 ms | 3.7 ms | | querySelectorAll('[attribute]') | 4.0 ms | 1.7 ms | | querySelectorAll('[class~="name"]') | 5.5 ms | 2.9 ms | | querySelectorAll(':nth-child(2n+1)') | 10.4 ms | 3.8 ms |

See how the test was done here

Jest

Happy DOM provide with a package called @happy-dom/jest-environment that makes it possible to use Happy DOM with Jest.

Vitest

Vitest supports Happy DOM out of the box.

Global Registration

Happy DOM provide with a package called @happy-dom/global-registrator that can register Happy DOM globally. It makes it possible to use Happy DOM for testing in a Node environment.

Sponsors