@tweenjs/tween.js

What is @tweenjs/tween.js?

@tweenjs/tween.js is a simple but powerful tweening engine for JavaScript. It allows you to create smooth animations by interpolating between values over time. This can be used for animating properties of objects, such as position, scale, rotation, and more.

What are @tweenjs/tween.js's main functionalities?

Basic Tweening

This code demonstrates basic tweening where an object's properties (x and y coordinates) are animated from one state to another over a duration of 1000 milliseconds.

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

let coords = { x: 0, y: 0 };
let tween = new TWEEN.Tween(coords)
  .to({ x: 100, y: 100 }, 1000)
  .onUpdate(() => {
    console.log(coords);
  })
  .start();

function animate(time) {
  requestAnimationFrame(animate);
  TWEEN.update(time);
}

requestAnimationFrame(animate);

Easing Functions

This code demonstrates the use of easing functions to create more natural motion. The Quadratic.Out easing function is used to slow down the animation towards the end.

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

let coords = { x: 0, y: 0 };
let tween = new TWEEN.Tween(coords)
  .to({ x: 100, y: 100 }, 1000)
  .easing(TWEEN.Easing.Quadratic.Out)
  .onUpdate(() => {
    console.log(coords);
  })
  .start();

function animate(time) {
  requestAnimationFrame(animate);
  TWEEN.update(time);
}

requestAnimationFrame(animate);

Chaining Tweens

This code demonstrates chaining tweens, where one tween starts after another finishes. The x coordinate is animated first, followed by the y coordinate.

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

let coords = { x: 0, y: 0 };
let tween1 = new TWEEN.Tween(coords)
  .to({ x: 100 }, 1000);
let tween2 = new TWEEN.Tween(coords)
  .to({ y: 100 }, 1000);

tween1.chain(tween2);
tween1.start();

function animate(time) {
  requestAnimationFrame(animate);
  TWEEN.update(time);
}

requestAnimationFrame(animate);

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README

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

	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)

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

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.

People

Maintainers: mikebolt, sole.

All contributors.

Projects using tween.js