title: Date difference in JQuery received NAN
body: <p>I am trying to calculate the days on Blur method of End Date. But I received 'NAN'.What at could be wrong? I received 'NAN'. </p>
  
  <pre><code>$('#EndDate').blur(function () {
  
     var diff = dateDiff($('#StartDate').val(), $('#EndDate').val());
      alert(diff);
  
  });
  
  function dateDiff(startDate, endDate) {
      return endDate.getDate() - startDate.getDate();
  }
  </code></pre>