Skip to content


Repository files navigation


JavaScript (TypeScript) tweening engine for easy animations, incorporating optimised Robert Penner's equations.

NPM Version CDNJS NPM Downloads Build and Tests

More languages: English, 简体中文


<script src=""></script>

<div id="box"></div>

	#box {
		background-color: deeppink;
		width: 100px;
		height: 100px;

	const box = document.getElementById('box') // Get the element we want to animate.

	const coords = {x: 0, y: 0} // Start at (0, 0)

	const tween = new TWEEN.Tween(coords, false) // Create a new tween that modifies 'coords'.
		.to({x: 300, y: 200}, 1000) // Move to (300, 200) in 1 second.
		.easing(TWEEN.Easing.Quadratic.InOut) // Use an easing function to make the animation smooth.
		.onUpdate(() => {
			// Called after tween.js updates 'coords'.
			// Move 'box' to the position described by 'coords' with a CSS translation.'transform', 'translate(' + coords.x + 'px, ' + coords.y + 'px)')
		.start() // Start the tween immediately.

	// Setup the animation loop.
	function animate(time) {

Try the above example on CodePen

Animate numbers in any JavaScript object. For example, rotate a 3D box made with Three.js:


From CDN

Install from a content-delivery network (CDN) like in the above example.

From cdnjs:

<script src=""></script>

Or from

<script src="^20.0.0/dist/tween.umd.js"></script>

Note that supports a semver version in the URL, where the ^ in the URL tells unpkg to give you the latest version 20.x.x.

Build and include in your project with script tag

Currently npm is required to build the project.

git clone
cd tween.js
npm install
npm run build

This will create some builds in the dist directory. There are currently two different builds of the library:

  • UMD : tween.umd.js
  • ES6 Module :

You are now able to copy tween.umd.js into your project, then include it with a script tag, which will add TWEEN to the global scope,

<script src="path/to/tween.umd.js"></script>

or import TWEEN as a JavaScript module,

<script type="module">
	import * as TWEEN from 'path/to/'

where path/to is replaced with the location where you placed the file.

With npm install and import from node_modules

You can add tween.js as an npm dependency:

npm install @tweenjs/tween.js

With a build tool

If you are using Node.js, Parcel, Webpack, Rollup, Vite, or another build tool, then you can now use the following to include tween.js:

import * as TWEEN from '@tweenjs/tween.js'

Without a build tool

You can import from node_modules if you serve node_modules as part of your website, using an importmap script tag. First, assuming node_modules is at the root of your website, you can write an import map:

<script type="importmap">
		"imports": {
			"@tweenjs/tween.js": "/node_modules/@tweenjs/tween.js/dist/"

Now in any of your module scripts you can import it by its package name:

import * as TWEEN from '@tweenjs/tween.js'


  • Does one thing and one thing only: tween properties
  • Doesn't take care of CSS units (e.g. appending px)
  • Doesn't interpolate colors
  • Easing functions are reusable outside of Tween
  • Can also use custom easing functions



hello world hello world
Bars Bars
Black and red Black and red
Graphs Graphs
Simplest possible example Simplest possible example
Video and time Video and time
Array interpolation Array interpolation
Dynamic to, object Dynamic to, object
Dynamic to, interpolation array Dynamic to, interpolation array
Dynamic to, large interpolation array Dynamic to, large interpolation array
Repeat Repeat
Relative values Relative values
Yoyo Yoyo
Stop all chained tweens Stop all chained tweens
Custom functions Custom functions
Relative start time Relative start time
Pause tween Pause tween
Complex properties Complex properties
Animate an array of values Animate an array of values


You need to install npm first--this comes with node.js, so install that one first. Then, cd to tween.js's (or wherever you cloned the repo) directory and run:

npm install

To run the tests run:

npm test

If you want to add any feature or change existing features, you must run the tests to make sure you didn't break anything else. Any pull request (PR) needs to have updated passing tests for feature changes (or new passing tests for new features or fixes) in src/tests.ts a PR to be accepted. See contributing for more information.


Maintainers: Joe Pea (@trusktr).

All contributors.

Projects using tween.js

Lume A-Frame VR MOMA Inventing Abstraction 1910-1925 Web Lab MACCHINA I Minesweeper 3D ROME WebGL Globe Androidify The Wilderness Downtown Linechart