happy-dom

A JavaScript implementation of a web browser without its graphical user interface.

DOM Features

• Custom Elements (Web Components)

• Declarative Shadow DOM

• Mutation Observer

• Tree Walker

• Fetch API

And much more..

Documentation

Documentation | Getting Started | Setup as Test Environment | GitHub

Works With

Vitest | Bun | Jest | Testing Library | Google LitElement | Vue | React | Svelte | Angular

Module Systems

ESM | CommonJS

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(':nth-child(2n+1)')	10.4 ms	3.8 ms

See how the test was done here