website/js/scroll.js

window.onload = (event) => {
  if ((document.documentElement.scrollHeight / window.screen.availHeight ) > 1.5) {
    window.addEventListener("scroll", () => {
      var winScroll = document.body.scrollTop || document.documentElement.scrollTop;
      var height = document.documentElement.scrollHeight - document.documentElement.clientHeight;
      var scrolled = (winScroll / height) * 100;
      document.getElementById('progress').style.width = scrolled + "%";

      const toTop = document.getElementById('totop');

      if ((window.scrollY > 0 && !toTop.classList.contains("show")) || (window.scrollY <= 0 && toTop.classList.contains("show"))) {
        toTop.classList.toggle("show");
      }
    });
  }
}