我如何根据使用jQuery提交的持续时间获取日期？

Question

我有一个during下拉列表，并且有三个字段3 months, 6 months & 1 year。然后我们有日期from和to。当我选择日期From时，则To中的日期将根据选定的持续时间增加。

我尝试了什么：-

/*$('.datePicker').datetimepicker({
        timepicker: false,
        format: 'm/d/Y'
    });
*/
    
 $(document).ready(function () {

       durationTermF();
       function durationTermF() {
       $('#durationTerm').on('change', function () {
           var durationTerm = $(this).find('option:selected').text();
           alert(durationTerm);
           })
       }

       $('body').on ('blur', '.pcFrom',function () {
           durationTermF();
           var fromDate = $(this).val();
           $('.pcTo').val(fromDate);

       });
   })

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
    
    <link rel="stylesheet" href="http://ethiomedical.ansitsdev.com/WebContent/plugins/datetimepicker/jquery.datetimepicker.css" />
    
    <script src="http://ethiomedical.ansitsdev.com/WebContent/plugins/datetimepicker/jquery.datetimepicker.js"></script>
    
    <div class="container">
        <br>
<div class="col-md-4">
    
    <div class="form-group">
        <label>Duration</label>
     <select class="form-control" id="durationTerm">
        <option>select</option>
       <option value="15">3 month</option>
       <option value="16">6 month</option>
       <option value="17">1 year</option>
    </select>
        </div>
    
    <div class="form-group">
        <label>From</label>
        <input type="text" class="form-control datePicker pcFrom">
        </div>
  
    <div class="form-group">
        <label>To</label>
        <input type="text" class="form-control pcTo">
        </div>
      </div>
    </div>