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Javascript tweening engine
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Updated readme examples to es6
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JavaScript tweening engine for easy animations, incorporating optimised Robert Penner's equations.

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

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

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.
  'transform', `translate(${coords.x}px, ${coords.y}px)`);
        .start(); // Start the tween immediately.

Test it with CodePen


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 @tweenjs/tween.js

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

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

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

const 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/tween.js --save

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


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 pull request (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

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