Javascript Easing Functions

A collection of configurable easing functions for Javascript.

Demo

See the demo that accompanies this repository for examples of each tween function.

Usage

Vanilla Javascript

Download the built file and include it in your project. Do not hotlink to this file!

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

Then reference the global "easing" variable:

// Pass in a value from 0 - 1 and get the eased value back
easing.easeInCube( 0.5 );

ES6

Install with npm install --save easing-utils

// Curly braces needed for import
import { easeInCubic, easeInOutBounce } from 'easing-utils';

// Pass in a value from 0 - 1 and get the eased value back
const eased = easeInCubic( 0.5 );

CommonJS

Install with npm install --save easing-utils

var easing = require('easing-utils');

// Pass in a value from 0 - 1 and get the eased value back
var eased = easing.easeInCubic( 0.5 );

API

All values are from 0 to 1.

Some functions take an optional magnitude argument. The ranges vary per function, and usually determine how far past zero the tween goes.

number:linear( value:number )

number:easeInSine( value:number )

number:easeOutSine( value:number )

number:easeInOutSine( value:number )

number:easeInQuad( value:number )

number:easeOutQuad( value:number )

number:easeInOutQuad( value:number )

number:easeInCubic( value:number )

number:easeOutCubic( value:number )

number:easeInOutCubic( value:number )

number:easeInQuart( value:number )

number:easeOutQuart( value:number )

number:easeInOutQuart( value:number )

number:easeInQuint( value:number )

number:easeOutQuint( value:number )

number:easeInOutQuint( value:number )

number:easeInExpo( value:number )

number:easeOutExpo( value:number )

number:easeInOutExpo( value:number )

number:easeInCirc( value:number )

number:easeOutCirc( value:number )

number:easeInOutCirc( value:number )

number:easeInBack( value:number, /*optional */magnitude:number )

number:easeOutBack( value:number, /*optional */magnitude:number )

number:easeInOutBack( value:number, /* optional */magnitude:number )

number:easeInElastic( value:number, /* optional */magnitude:number )

number:easeOutElastic( value:number, /* optional */magnitude:number )

number:easeInOutElastic( value:number, /* optional */magnitude )

number:easeOutBounce( value:number )

number:easeInBounce( value:number )

easeInOutBounce( value:number )

Development

First install all dependencies:

npm install

To build the standalone Javascript file, run:

npm run build-cdn

The output is put in the dist/ folder.

The website deployed here lives in the gh-pages/ folder. To deploy the website, run npm run gh-pages. Then go to http://[your username].github.io/easing-utils/gh-pages/. Out of laziness, I have not yet set up a development server to work on the Github pages.

About

What does this library have that others don't?

There's a few other easing libraries out there, but none of them met my needs, which are:

• Fully documented
• Configurable easing functions where available
• Examples presented clearly
• Available through npm
• High quality, readable source code
• Only take a single parameter, which is the initial value from 0 to 1