<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>

document.addEventListener('DOMContentLoaded', () => {
  const gl = document.createElement('canvas').getContext('webgl');
  const a = gl.getExtension('EXT_disjoint_timer_query');
  const b = a.createQueryEXT();
  a.queryCounterEXT(b, a.TIMESTAMP_EXT);
  a.deleteQueryEXT(b);
});

</script>
</head>
</html>
