Javascript tweening engine
JavaScript CSS Other


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

NPM Version NPM Downloads Travis tests Flattr this CDNJS

var coords = { x: 0, y: 0 };
var tween = new TWEEN.Tween(coords)
    .to({ x: 100, y: 100 }, 1000)
    .onUpdate(function() {
        console.log(this.x, this.y);


function animate(time) {


Download the library and include it in your code:

<script src="js/Tween.js"></script>

You can also reference a CDN-hosted version in your code, thanks to cdnjs. For example:

<script src=""></script>

See tween.js for more versions.

More advanced users might want to...

Use npm

npm install tween.js

Then include the Tween.js module with the standard node.js require:

var TWEEN = require('tween.js');

And you can use Tween.js as in all other examples--for example:

var t = new TWEEN.Tween( /* etc */ );

You will need to use a tool such as browserify to convert code using this style into something that can be run in the browser (browsers don't know about require).

Use bower

bower install tweenjs --save

or install an specific tag. They are git tags, and you can run git tag in the command line for a list if you have cloned the repository locally, or you can also check out the list in the tween.js tags page. For example, to install v16.3.0:

bower install tweenjs#v16.3.0

Then reference the library source:

<script src="bower_components/tweenjs/src/Tween.js"></script>


  • 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



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


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

if running the tests for the first time, to install additional dependencies for running tests, and then run

npm test

every time you want to run the tests.

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. If you send a PR to add something new and it doesn't have tests, or the tests don't pass, the PR won't be accepted. See contributing for more information.


Maintainers: mikebolt, sole.

All contributors.

Projects using tween.js

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