Skip to content

Instantly share code, notes, and snippets.

@gre
Last active October 30, 2024 16:49
Show Gist options
  • Save gre/1650294 to your computer and use it in GitHub Desktop.
Save gre/1650294 to your computer and use it in GitHub Desktop.
Simple Easing Functions in Javascript - see https://github.com/gre/bezier-easing
/*
* This work is free. You can redistribute it and/or modify it under the
* terms of the Do What The Fuck You Want To Public License, Version 2,
* as published by Sam Hocevar. See the COPYING file for more details.
*/
/*
* Easing Functions - inspired from http://gizma.com/easing/
* only considering the t value for the range [0, 1] => [0, 1]
*/
EasingFunctions = {
// no easing, no acceleration
linear: t => t,
// accelerating from zero velocity
easeInQuad: t => t*t,
// decelerating to zero velocity
easeOutQuad: t => t*(2-t),
// acceleration until halfway, then deceleration
easeInOutQuad: t => t<.5 ? 2*t*t : -1+(4-2*t)*t,
// accelerating from zero velocity
easeInCubic: t => t*t*t,
// decelerating to zero velocity
easeOutCubic: t => (--t)*t*t+1,
// acceleration until halfway, then deceleration
easeInOutCubic: t => t<.5 ? 4*t*t*t : (t-1)*(2*t-2)*(2*t-2)+1,
// accelerating from zero velocity
easeInQuart: t => t*t*t*t,
// decelerating to zero velocity
easeOutQuart: t => 1-(--t)*t*t*t,
// acceleration until halfway, then deceleration
easeInOutQuart: t => t<.5 ? 8*t*t*t*t : 1-8*(--t)*t*t*t,
// accelerating from zero velocity
easeInQuint: t => t*t*t*t*t,
// decelerating to zero velocity
easeOutQuint: t => 1+(--t)*t*t*t*t,
// acceleration until halfway, then deceleration
easeInOutQuint: t => t<.5 ? 16*t*t*t*t*t : 1+16*(--t)*t*t*t*t
}
@temm1210
Copy link

really awesome and useful!! Thank you!!

@aarongeorge
Copy link

aarongeorge commented Oct 5, 2020

Great gist @gre!

I thought it might be helpful to those who wanted to extend the curves to see how that could be done using higher order functions and increasing the power (Thanks to @lindell for the original snippet! This version however removes the unnecessary Math.abs, reuses easeIn for the easeOut function and changes linear to reference easeIn rather than easeInOut to reduce the complexity for each call (although this definitely isn't an exercise in performance))

const easeIn = p => t => Math.pow(t, p)
const easeOut = p => t => 1 - easeIn(p)(1 - t)
const easeInOut = p => t => t < .5 ? easeIn(p)(t * 2) / 2 : easeOut(p)(t * 2 - 1) / 2 + .5
const Easings = {
	linear: easeIn(1),
	easeInQuad: easeIn(2),
	easeOutQuad: easeOut(2),
	easeInOutQuad: easeInOut(2),
	easeInCubic: easeIn(3),
	easeOutCubic: easeOut(3),
	easeInOutCubic: easeInOut(3),
	easeInQuart: easeIn(4),
	easeOutQuart: easeOut(4),
	easeInOutQuart: easeInOut(4),
	easeInQuint: easeIn(5),
	easeOutQuint: easeOut(5),
	easeInOutQuint: easeInOut(5)
}

Knowing this, you can re-write @gre's gist like so:

const Easings = {
	linear = t => t,
	easeInQuad = t => Math.pow(t, 2),
	easeOutQuad = t => 1 - Math.pow(1 - t, 2),
	easeInOutQuad = t => t < .5 ? Math.pow(t * 2, 2) / 2 : (1 - Math.pow(1 - (t * 2 - 1), 2)) / 2 + .5,
	easeInCubic = t => Math.pow(t, 3),
	easeOutCubic = t => 1 - Math.pow(1 - t, 3),
	easeInOutCubic = t => t < .5 ? Math.pow(t * 2, 3) / 2 : (1 - Math.pow(1 - (t * 2 - 1), 3)) / 2 + .5,
	easeInQuart = t => Math.pow(t, 4),
	easeOutQuart = t => 1 - Math.pow(1 - t, 4),
	easeInOutQuart = t => t < .5 ? Math.pow(t * 2, 4) / 2 : (1 - Math.pow(1 - (t * 2 - 1), 4)) / 2 + .5,
	easeInQuint = t => Math.pow(t, 5),
	easeOutQuint = t => 1 - Math.pow(1 - t, 5),
	easeInOutQuint = t => t < .5 ? Math.pow(t * 2, 5) / 2 : (1 - Math.pow(1 - (t * 2 - 1), 5)) / 2 + .5
}

Although it is much more verbose, hopefully it's easier to understand for those who don't understand the pre-decrement tricks

Finally you can take the previous example and substitute parts of the equations to reference each other (cleaning it up a little bit)

const linear = t => t
const easeInQuad = t => Math.pow(t, 2)
const easeOutQuad = t => 1 - easeInQuad(1 - t)
const easeInOutQuad = t => t < .5 ? easeInQuad(t * 2) / 2 : easeOutQuad(t * 2 - 1) / 2 + .5
const easeInCubic = t => Math.pow(t, 3)
const easeOutCubic = t => 1 - easeInCubic(1 - t)
const easeInOutCubic = t => t < .5 ? easeInCubic(t * 2) / 2 : easeOutCubic(t * 2 - 1) / 2 + .5
const easeInQuart = t => Math.pow(t, 4)
const easeOutQuart = t => 1 - easeInQuart(1 - t)
const easeInOutQuart = t => t < .5 ? easeInQuart(t * 2) / 2 : easeOutQuart(t * 2 - 1) / 2 + .5
const easeInQuint = t => Math.pow(t, 5)
const easeOutQuint = t => 1 - easeInQuint(1 - t)
const easeInOutQuint = t => t < .5 ? easeInQuint(t * 2) / 2 : easeOutQuint(t * 2 - 1) / 2 + .5

@therealparmesh
Copy link

Great thread!

@gre
Copy link
Author

gre commented Apr 20, 2021

@aarongeorge thanks a lot! this is super useful! specifically, recently I was wondering how to generate it to any pow, I used this to something unrelated to easing but to do "distribution" => https://greweb.me/plots/109 (making my lines reaching more the edges)

@aarongeorge
Copy link

@gre glad I could return the favour! Full credit to @lindell for the original Higher Order implementation. I just wanted to break it down and tweak a few things so it benefits more people.

Copy link

ghost commented Nov 24, 2021

An alternative (works somehow)

eval(function(p,a,c,k,e,d){e=function(c){return c.toString(36)};if(!''.replace(/^/,String)){while(c--){d[c.toString(a)]=k[c]||c.toString(a)}k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1};while(c--){if(k[c]){p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c])}}return p}('f d={c:3(n){0 n},g:3(n){0 n*n},a:3(n){0 n*(2-n)},7:3(n){0 n<.5?2*n*n:(4-2*n)*n-1},9:3(n){0 n*n*n},b:3(n){0--n*n*n+1},e:3(n){0 n<.5?4*n*n*n:(n-1)*(2*n-2)*(2*n-2)+1},k:3(n){0 n*n*n*n},h:3(n){0 1- --n*n*n*n},i:3(n){0 n<.5?8*n*n*n*n:1-8*--n*n*n*n},l:3(n){0 n*n*n*n*n},j:3(n){0 1+--n*n*n*n*n},m:3(n){0 n<.5?6*n*n*n*n*n:1+6*--n*n*n*n*n}};',24,24,'return|||function|||16|easeInOutQuad||easeInCubic|easeOutQuad|easeOutCubic|linear|EasingFunctions|easeInOutCubic|var|easeInQuad|easeOutQuart|easeInOutQuart|easeOutQuint|easeInQuart|easeInQuint|easeInOutQuint|'.split('|'),0,{}))

@nukadelic
Copy link

visual cheat sheet https://easings.net/

@phil-green-CTI
Copy link

This is really good but the easing functions are causing me trouble. I would like the first 75% of the count to go very quickly, and then decelerate to a crawl. I what would the proper function be for this? I imagine something like:

const easeOut = t<.75 ? t => t : [SOMETHING] ;

but I don't know what to put there.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment