jQuery actual validation with From date and to date validation.
1. 
If from date is selected then to date will be
>= from date
2. 
If to date selected first then from date will
be <= to date
$(document).ready(function
() {
           
$("#<%=txtCreateDtFrom.ClientID %>").prop('readonly',
true);
           
$("#<%=txtCreateDtTo.ClientID %>").prop('readonly',
true);
           
$("#<%=txtDeadlineFrom.ClientID %>").prop('readonly',
true);
           
$("#<%=txtDeadlineTo.ClientID %>").prop('readonly',
true);
           
$(".calendar-drop").datepicker({
                changeMonth: true,
                changeYear: true
            });
           
$("#<%=txtCreateDtFrom.ClientID %>").datepicker({
                changeMonth: true,
                changeYear: true,
                beforeShow: function () {
                    dt =
$("#<%=txtCreateDtTo.ClientID %>").datepicker('getDate');
                    return { maxDate: dt };
                }
            });
           
$("#<%=txtCreateDtTo.ClientID %>").datepicker({
                changeMonth: true,
                changeYear: true,
                beforeShow: function () {
                    dt =
$("#<%=txtCreateDtFrom.ClientID %>").datepicker('getDate');
                    return { minDate: dt };
                }
            });
            $("#<%=txtDeadlineFrom.ClientID
%>").datepicker({
                changeMonth: true,
                changeYear: true,
                beforeShow: function () {
                    dt =
$("#<%=txtDeadlineTo.ClientID %>").datepicker('getDate');
                    return { maxDate: dt };
                }
            });
           
$("#<%=txtDeadlineTo.ClientID %>").datepicker({
                changeMonth: true,
                changeYear: true,
                beforeShow: function () {
                    dt =
$("#<%=txtDeadlineFrom.ClientID %>").datepicker('getDate');
                    return { minDate: dt };
                }
            });           
});           
