title: Javascript Date.now() function returning null
body: <p>So I have the following segment of code:</p>
  
  <pre><code>//Main game loop
  var main = function () {
  
      var now = Date.now();
      var delta = now - then;
      update(delta / 1000);
      render();
      then = now;
      //Request to perform again
      requestAnimationFrame(main);
  };
  </code></pre>
  
  <p>and while debugging I came across a pretty strange error.
  It's returning the <strong>then</strong> variable, but returning null for the <strong>now</strong> variable.</p>
  
  <p>Any help would be greatly appreciated! Been scratching my head at this for a while!
  Thanks in advance! :) </p>