<html>
<body>
  <p> Counting up every 50ms </p>
  <input id="input" value="0"/>
  <script>
  window.addEventListener('load', function() {
    var inputElement = document.getElementById('input');
    window.setInterval(function() {
      inputElement.value = inputElement.value * 1 + 1;
    }, 50);
  });
  </script>
</body>
</html>