<!DOCTYPE html>
<body>
<div id='testElement' style='display: none'>TEST</div>
<script>
setInterval(function() {
  // Change the style of a display:none element.
  var testElement = document.getElementById("testElement");
  testElement.style["left"] = "" + Math.floor((Math.random() * 10) + 1) + "px";
}, 0);
</script>
</body>