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18.6.1 • Public • Published


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

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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. v18 is not yet available on CDNJS.

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


Currently npm is required to build the project.

git clone
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 :

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');


  • 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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  • alexrodin