Custom Validator

 <asp:CustomValidator runat="server" ID="cvCurrentDate" SetFocusOnError="true" ClientValidationFunction="ValidateAuditCurrentDate"
                                            Display="None" ValidationGroup="save"></asp:CustomValidator>




//modified by raveesh malhotra on september 30
        function ValidateAuditCurrentDate(source, args) {
            
            var StartDate = document.getElementById('<%= txtStartDate.ClientID %>').value;
            var EndDate = document.getElementById('<%= txtEndDate.ClientID %>').value;
            var CurrentDate = new Date();
            CurrentDate= CurrentDate.format('dd-mmm-yyyy')
       
         
           var StartDateday = StartDate.substring(0,2);
            var StartDatemonth = StartDate.substring(3,6);
            var StartDateyear = StartDate.substring(7,11);

            var EndDateday= EndDate.substring(0,2);
            var EndDatemonth = EndDate.substring(3,6);
            var EndDateyear = EndDate.substring(7,11);

            var CurrentDateday = CurrentDate.substring(0,2);
            var CurrentDatemonth = CurrentDate.substring(3,6);
            var CurrentDateyear = CurrentDate.substring(7,11);

            StartDatemonth=changeFormatStringtoNumber(StartDatemonth);
            EndDatemonth=changeFormatStringtoNumber(EndDatemonth);
            CurrentDatemonth=changeFormatStringtoNumber(CurrentDatemonth);
       
            var StartDate=new Date(StartDateyear,StartDatemonth,StartDateday);
            var EndDate = new Date(EndDateyear, EndDatemonth, EndDateday);
            var CurrentDate = new Date(CurrentDateyear, CurrentDatemonth,CurrentDateday );
        
       

             if (StartDate != "" || EndDate != "")
             {
                         
              if(StartDate < CurrentDate || EndDate< CurrentDate ||  StartDate > EndDate)
              {
                args.IsValid = false;       
                return;
              }

             }
             args.IsValid = true;
        }