var prevScrollpos = window.pageYOffset;
    window.onscroll = function() {
      var currentScrollPos = window.pageYOffset;
      var element = document.getElementById("hideOnScroll");
      if (prevScrollpos < currentScrollPos) {            
        element.classList.add("topHide");
      } else {
        element.classList.remove("topHide");
      }
      prevScrollpos = currentScrollPos;
    };