How can I make this JavaScript interval random?
<p>How do I make this interval from every 2 seconds to randomly X - X seconds? Also, how do I change the increment from every 2 increments as well to randomly X - X? If you see a flaw in my code or improvement needed please as well let me know, in separate code if willing. Much appreciated.</p>

<pre><code>&lt;div id="counter"&gt;&lt;/div&gt;
&lt;script type="text/javascript"&gt;
  var START_DATE = new Date("January 1, 2012 12:00:00"); // put in the starting date here
  var INTERVAL    = 2; // in seconds
  var INCREMENT   = 2; // increase per tick
  var START_VALUE = 5000; // initial value when it's the start date
  var count = 0;
  window.onload = function()
  {
    var msInterval = INTERVAL * 2000;
    var now = new Date();
    count = parseInt((now - START_DATE)/msInterval) * INCREMENT + START_VALUE;
    document.getElementById('counter').innerHTML = count;
    setInterval(
      "count += INCREMENT; document.getElementById('counter').innerHTML = count;", msInterval);
  }
&lt;/script&gt;
</code></pre>
