Add days to Date in Javascript

select 10 20 20 90
 

 

 

<input id="date" type="text" value="10-12-202" />
<select id="terms" onchange="return dueDate()">
  <option value=""></option>
  <option value="10">10</option>
  <option value="20">20</option>
  <option value="20">20</option>
  <option value="90">90</option>
</select>
<input id="due_date" readonly="" type="text" />

<script>

function dueDate(){
  var terms=parseFloat (document.getElementById("terms").value);

  var inv_date=document.getElementById("date").value;

  var res = inv_date.split("-");
  inv_date = res[2]+"-"+res[1]+"-"+res[0];

  var today =new Date(inv_date);
  var dueDate =new Date(inv_date).setDate(today.getDate()+terms);
  var newDate = new Date(dueDate);
  //alert(newDate);
  //newDate = newDate.toLocaleString();
  var date = newDate.getDate();
  date = (date &lt;= 9) ? '0'+date : date;
  var month = newDate.getMonth()+1;
  month = (month &lt;= 9) ? '0'+month : month;

  var year = newDate.getFullYear();
  //alert(month);
  document.getElementById("due_date").value=date+"-"+month+"-"+year;
}
</script>