What's the best way to calculate date difference in Javascript
<p>I doing a function in Javascript like the VisualBasic DateDiff.</p>

<p>You give two dates and the returning time interval (Seconds, Minutes, Days, etc...)</p>

<pre><code>DateDiff(ByVal Interval As Microsoft.VisualBasic.DateInterval, _
  ByVal Date1 As Date, ByVal Date2 As Date) as Long
</code></pre>

<p>So what's the best way to calculate the difference of Javascript Dates?</p>
