tween.js

JavaScript tweening engine for easy animations, incorporating optimised Robert Penner’s equations.

Update Note In v18 the script you should include has moved from src/Tween.js to dist/tween.umd.js. See the installation section below.

const box = document.createElement('div')
box.style.setProperty('background-color', '#008800')
box.style.setProperty('width', '100px')
box.style.setProperty('height', '100px')
document.body.appendChild(box)

// Setup the animation loop.
function animate(time) {
	requestAnimationFrame(animate)
	TWEEN.update(time)
}
requestAnimationFrame(animate)

const coords = {x: 0, y: 0} // Start at (0, 0)
const tween = new TWEEN.Tween(coords) // Create a new tween that modifies 'coords'.
	.to({x: 300, y: 200}, 1000) // Move to (300, 200) in 1 second.
	.easing(TWEEN.Easing.Quadratic.Out) // 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.
		box.style.setProperty('transform', `translate(${coords.x}px, ${coords.y}px)`)
	})
	.start() // Start the tween immediately.

Test it with CodePen

Installation

Currently npm is required to build the project.

git clone https://github.com/tweenjs/tween.js
cd tween.js
npm i .
npm run build

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

UMD : tween.umd.js
AMD : tween.amd.js
CommonJS : tween.cjs.js
ES6 Module : tween.es.js

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

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

With `require('@tweenjs/tween.js')`

You can add tween.js as an npm dependency:

npm i @tweenjs/tween.js@^18

If you are using Node, Webpack, or Browserify, then you can now use the following to include tween.js:

const TWEEN = require('@tweenjs/tween.js')

Features

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

Documentation

User guide
Contributor guide
Tutorial using tween.js with three.js
Also: libtween, a port of tween.js to C by jsm174
Also: es6-tween, a port of tween.js to ES6/Harmony by dalisoft
Understanding tween.js

Examples

	hello world (source)		Bars (source)
	Black and red (source)		Graphs (source)
	Simplest possible example (source)		Video and time (source)
	Array interpolation (source)		Dynamic to (source)
	Dynamic to (source)		Dynamic to (source)
	Repeat (source)		Relative values (source)
	Yoyo (source)		Stop all chained tweens (source)
	Custom functions (source)		Custom functions (source)
	Custom functions (source)		Custom functions (source)
	Custom functions (source)

Tests

You need to install npm first–this comes with node.js, so install that one first. Then, cd to tween.js’s 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) in src/tests.ts, otherwise the PR won’t be accepted. See contributing for more information.