Find Number of days between two given dates in Javascript

My question is Find number of days between the two given dates by using javascript. See below code, copy and paste the code into your html page in head tag.

<script>
function   DiffInDays(startDate, endDate){
      startDate = new Date(startDate);
      endDate = new Date(endDate);
      if(endtDate.getTime() > startDate.getTime())
      {
             var diffDays = endDate.getDate() - startDate.getDate();
             alert("Difference in Days :"+diffDays/86400000);// MilliSeconds for one day is 1000*60*60*24
       }
       else  if(endtDate.getTime() == startDate.getTime()){
             alert("StartDate and endDate are equal");
       }
       
}
</script>