Microsoft Technical Issues

There is not a method to validate future or past date in Ajax CalendarExtender Control. This is the JavaScript to set validate the Ajax calendar for future date. If you want to validate past date ,you have to do only change the comparison symbol.

    <script language="javascript" type="text/javascript">
        function checkDate(sender,args)
            {       
                if (sender._selectedDate < new Date())
                {
                    alert("You must select a date in the future.");
                   
                    //create the date
                    var myDate = new Date();
                    //add a day to the date
                    myDate.setDate(myDate.getDate() + 1);
                    sender._selectedDate = myDate;  //new Date();
                    // set the date back to the current date
                    sender._textbox.set_Value(sender._selectedDate.format(sender._format))
                }

            }

    </script>