page scroll indicator research

HTML

<div class="progress-fixed">
  <div class="progress-bar-container">
    <div class="progress-bar" id="myBar"></div>
  </div>
</div>

CSS

.progress-fixed {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 1;
  width: 100%;
  background-color: #f1f1f1;
}

.progress-bar-container {
  width: 100%;
  height: 5px;
  background: #ccc;
}

.progress-bar {
  height: 5px;
  background: #f04b4b;
  width: 0%;
}

Javascript

window.onscroll = function() {myFunction()};

function myFunction() {
  var winScroll = document.body.scrollTop || document.documentElement.scrollTop;
  var height = document.documentElement.scrollHeight - document.documentElement.clientHeight;
  var scrolled = (winScroll / height) * 100;
  document.getElementById("myBar").style.width = scrolled + "%";
}