scroll-direction-detect.js

var lastScrollTop = 0;
// element should be replaced with the actual target element on which you have applied scroll, use window in case of no target element.
element.addEventListener("scroll", function(){ // or window.addEventListener("scroll"....
   var st = window.pageYOffset || document.documentElement.scrollTop; // Credits: "https://github.com/qeremy/so/blob/master/so.dom.js#L426"
   if (st > lastScrollTop){
       // downscroll code
   } else {
      // upscroll code
   }
   lastScrollTop = st;
}, false);