Easing

A collection of animation easing functions in Javascript's ES6 module format. Easing functions specify the rate of change of a parameter over time. Learn more about easing here.

Install

Easing is an ES6 module. Consequently, you'll need an ES6 transpiler (Babel is a nice one) and a module loader (SystemJS will do the job) as part of your Javascript workflow.

If you're already using the JSPM package manager for your project, you can install Easing with the following command:

$ jspm install github:DEGJS/easing

Usage

import { easeInOutCubic } from 'DEGJS/easing';

// animate a value from 100 to 300 with ease-in-out easing over the course of 1 second
let currentIteration = 0,
	totalIterations = 60,
	startValue = 100,
	changeInValue = 200,
	easedValue;

window.requestAnimationFrame(onAnimationFrame);

function onAnimationFrame() {
	if(currentIteration < totalIterations) {
		currentIteration++;
		easedValue = easeInOutCubic(currentIteration, startValue, changeInValue, totalIterations);
	}
}

Methods

All methods take the same four parameters, defined below:

currentIteration

Type: Number
The current iteration. Think of this in terms of animation frames or seconds/milliseconds.

startValue

Type: Number The start value. This is the initial state of the value that will be animated.

changeInValue

Type: Number The amount of change in the value over the duration of the animation.

totalIterations

The duration of the animation. Think of this in terms of animation frames or seconds/milliseconds.

.linear(currentIteration, startValue, changeInValue, totalIterations)

A linear rate of change with no easing.

.easeOutCubic(currentIteration, startValue, changeInValue, totalIterations)

Starts quickly and ends slowly.

.easeInCubic(currentIteration, startValue, changeInValue, totalIterations)

Starts slowly and ends quickly.

.easeInOutCubic(currentIteration, startValue, changeInValue, totalIterations)

Starts and ends slowly.

Browser Support

Easing does not depend on any special browser APIs and should work with all browsers.