window.requestAnimFrame = (function(callback) {
  return (
    window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    function(callback) {
      window.setTimeout(callback, 1000 / 30);
    }
  );
})();

stats = new Stats();
stats.setMode(0);
stats.domElement.style.position = 'fixed';
stats.domElement.style.left = '0px';
stats.domElement.style.top = '0px';
document.body.appendChild(stats.domElement);

function setStats() {
  stats.begin();
  requestAnimFrame(function() {
    stats.end();
    setStats();
  });
}

setStats();