scrolldir/dist/scrolldir.min.js

Vertical scroll direction in CSS

/**
 * scrolldir - Vertical scroll direction in CSS
 * @version v1.2.15
 * @link https://github.com/dollarshaveclub/scrolldir.git
 * @author Patrick Fisher <patrick@pwfisher.com>
 * @license MIT
**/
!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):t.scrollDir=e()}(this,function(){"use strict";function t(){var t=o.scrollY||o.pageYOffset,e=l.timeStamp,i="down"===d?Math.max:Math.min,p=f.offsetHeight-o.innerHeight;if(t=Math.max(0,t),t=Math.min(p,t),c.unshift({y:t,t:e}),c.pop(),t===i(m,t))return v=e,void(m=t);var b=e-a;if(b>v){m=t;for(var h=0;h<u&&(c[h]&&!(c[h].t<b));h+=1)m=i(m,c[h].y)}Math.abs(t-m)>s&&(m=t,v=e,d="down"===d?"up":"down",n.setAttribute(r,d))}function e(e){return l=e,o.requestAnimationFrame(t)}var i={el:document.documentElement,win:window,attribute:"data-scrolldir",dir:"down"},n=void 0,o=void 0,r=void 0,d=void 0,f=document.body,u=32,a=512,s=64,c=Array(u),l=void 0,m=void 0,v=0;return function(t){return n=t&&t.el||i.el,o=t&&t.win||i.win,r=t&&t.attribute||i.attribute,d=t&&t.direction||i.dir,t&&!0===t.off?(n.setAttribute(r,"off"),o.removeEventListener("scroll",e)):(m=o.scrollY||o.pageYOffset,n.setAttribute(r,d),o.addEventListener("scroll",e))}});