以下是答案...

 function GetDate(str) {
        debugger; 
                var arr = str.split('-');
               var months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun','Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
               var i = 1; 
               for (i; i <= months.length; i++) { 
                      if (months[i] == arr[1])
                       {                   
                         break;                     
                       } 
                  }
                  var formatddate = i  + '/' + arr[0] + '/' + arr[2]; 
                  return formatddate;
            }



 function StartDateTimeEndDate() {
                 var startDate = document.getElementById('<%=EFF_START_DATEDVTextBox.ClientID %>').value
                 var endDate = document.getElementById('<%=EFF_END_DATEDVTextBox.ClientID %>').value  
                 var startdt = GetDate(startDate)
                 var enddt = GetDate(endDate) 

               if ((Date.parse(enddt) <= Date.parse(startdt))) {
                alert("End date should be greater than Start date");
                document.getElementById('<%=EFF_END_DATEDVTextBox.ClientID %>').value = "";
                 } 
        }