Simple Easing Functions in Javascript - see https://github.com/gre/bezier-easing

easing.js

/*
 * 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
}

@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)

@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.

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,{}))

visual cheat sheet https://easings.net/

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.