scroll down up js

1var lastScrollTop = 0;
2
3// element should be replaced with the actual target element on which you have applied scroll, use window in case of no target element.
4element.addEventListener("scroll", function(){ // or window.addEventListener("scroll"....
5   var st = window.pageYOffset || document.documentElement.scrollTop; // Credits: "https://github.com/qeremy/so/blob/master/so.dom.js#L426"
6   if (st > lastScrollTop){
7      // downscroll code
8   } else {
9      // upscroll code
10   }
11   lastScrollTop = st <= 0 ? 0 : st; // For Mobile or negative scrolling
12}, false);
13