check scroll up js code example

Example 1: scroll down up 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 <= 0 ? 0 : st; // For Mobile or negative scrolling
}, false);

Example 2: how to keep scrolling with javascript

function scrolldown() {
  setTimeout(
    function()
    {
      window.scrollTo(0,document.body.scrollHeight);
      scrolldown();
    }, 2000
  )
}

scrolldown()