title: Add days in a date
body: <p>I have a function that add a number of days in a date. But the problem is .setDate is not a function. Here's my code. </p>
  
  <pre><code>$('#term').on('change',function(){
      var datepo = Aug-10-2016
      var days = 35
      var po_date = $.datepicker.formatDate('yy-m-d', new Date(datepo));
      po_date.setDate(po_date + parseInt(days)) 
  
      alert(po_date)
  })
  </code></pre>