Geting difference between to dates in days

<script language="JavaScript">

var difference = 0;

startdate = new Date("4/16/2008");

enddate = new Date("4/17/2008");

difference = enddate - startdate;
days = Math.round(difference/(1000*60*60*24));
alert(days);
</script>

<script type="text/javascript">
function dateDifference(startDate,endDate) {
    startdate = new Date(startDate);
    endDate  = new Date(endDate);
    difference = enddate - startdate;
    days = Math.round(difference/(1000*60*60*24));
    return days;
}
alert(dateDifference('4/16/2008','4/26/2008');
</script>