text: window.onscroll = function()
  {
      if (document.documentElement.scrollTop > 15)
      {
          document.querySelector(".button").classList.add("show");
      }
  
      else
      {
          document.querySelector(".button").classList.remove("show");
      }
  }
  
  document.querySelector(".button").addEventListener("click", ScrollUp);
  function ScrollUp()
  {
      var currentScroll = document.documentElement.scrollTop || document.body.scrollTop;
      if (currentScroll > 0)
      {
          window.requestAnimationFrame(ScrollUp);
          window.scrollTo (0, currentScroll - (currentScroll/7));
      }
  }