@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 (TypeScript) tweening engine for easy animations, incorporating optimised Robert Penner's equations.

---

<script src="https://cdnjs.cloudflare.com/ajax/libs/tween.js/20.0.0/tween.umd.js"></script>

<div id="box"></div>

<style>
	#box {
		background-color: deeppink;
		width: 100px;
		height: 100px;
	}
</style>

<script>
	const box = document.getElementById('box') // Get the element we want to animate.

	const coords = {x: 0, y: 0} // Start at (0, 0)

	const tween = new TWEEN.Tween(coords, false) // Create a new tween that modifies 'coords'.
		.to({x: 300, y: 200}, 1000) // Move to (300, 200) in 1 second.
		.easing(TWEEN.Easing.Quadratic.InOut) // 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.

	// Setup the animation loop.
	function animate(time) {
		tween.update(time)
		requestAnimationFrame(animate)
	}
	requestAnimationFrame(animate)
</script>

Try this example on CodePen

Installation

From CDN

Install from a content-delivery network (CDN) like in the above example.

From cdnjs:

<script src="https://cdnjs.cloudflare.com/ajax/libs/tween.js/20.0.0/tween.umd.js"></script>

Or from unpkg.com:

<script src="https://unpkg.com/@tweenjs/tween.js@^20.0.0/dist/tween.umd.js"></script>

Note that unpkg.com supports a semver version in the URL, where the ^ in the URL tells unpkg to give you the latest version 20.x.x.

Build and include in your project with script tag

Currently npm is required to build the project.

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

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

• UMD : tween.umd.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, which will add TWEEN to the global scope,

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

or import TWEEN as a JavaScript module,

<script type="module">
	import * as TWEEN from 'path/to/tween.es.js'
</script>

where path/to is replaced with the location where you placed the file.

With npm install and import from node_modules

You can add tween.js as an npm dependency:

npm install @tweenjs/tween.js

With a build tool

If you are using Node.js, Parcel, Webpack, Rollup, Vite, or another build tool, then you can now use the following to include tween.js:

import * as TWEEN from '@tweenjs/tween.js'

Without a build tool

You can import from node_modules if you serve node_modules as part of your website, using an importmap script tag. First, assuming node_modules is at the root of your website, you can write an import map:

<script type="importmap">
	{
		"imports": {
			"@tweenjs/tween.js": "/node_modules/@tweenjs/tween.js/dist/tween.es.js"
		}
	}
</script>

Now in any of your module scripts you can import it by its package name:

import * as TWEEN from '@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 colors
• 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
• 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, object (source)
	Dynamic to, interpolation array (source)		Dynamic to, large interpolation array (source)
	Repeat (source)		Relative values (source)
	Yoyo (source)		Stop all chained tweens (source)
	Custom functions (source)		Relative start time (source)
	Pause tween (source)		Complex properties (source)
	Animate an array of values (source)

Tests

You need to install npm first--this comes with node.js, so install that one first. Then, cd to tween.js's (or wherever you cloned the repo) 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 or fixes) in src/tests.ts a PR to be accepted. See contributing for more information.

People

Maintainers: mikebolt, sole, Joe Pea (@trusktr).

All contributors.

Projects using tween.js