How to validate & compare hours part of sharepoint datetime control?

Question

I have two sharepoint datetime controls where timeOnly=true. I need to validate as required field & validate as one controls Hours value must be Greater than & Equal to other one. I want to do it in Client side.

Note: Using timeOnly="true" means need to validate Hours & minutes Only.

Answer 1

Created an asp.net custom validator to compare hours & minutes part of two datetime controls.
And called javascript function from ClientValidationFunction property of asp.net custom validator.
Function is here:

        function ValidateHour&Minute(sender, args){
            var startDateHour = document.getElementById("<%=DateTimeControlStartDate.Controls[1].ClientID %>").value;// gets value from hours dropdown list for 1st datetime control
            var startDateMinute = document.getElementById("<%=DateTimeControlStartDate.Controls[2].ClientID %>").value;// gets value from minutes dropdown list for 1st datetime control
            var timeStart = new Date();
            var timeEnd = new Date();
            var strStartHour;
            var hourType;
            hourType = startDateHour.split(' '); 
            if (hourType[1] == "AM") {
                startDateHour=startDateHour.split(' ');
                strStartHour = startDateHour[0];
            }
            else {
                startDateHour=startDateHour.split(' '); 
                strStartHour = startDateHour[0]; 
                strStartHour = parseInt(strStartHour) + 12; 
            }
            timeStart.setHours(strStartHour, startDateMinute, 0, 0); 
            var strEndHour;
            var endDateHour = document.getElementById("<%=DateTimeControlEndDate.Controls[1].ClientID %>").value;// gets value from hours dropdown list for 2nd datetime control
            var endDateMinute = document.getElementById("<%=DateTimeControlEndDate.Controls[2].ClientID %>").value;// gets value from minutes dropdown list for 2nd datetime control
            hourType = endDateHour.split(' ');
            if (hourType[1] == "AM") {
                endDateHour=endDateHour.split(' ');
                strEndHour = endDateHour[0]; 
            }
            else {
                endDateHour= endDateHour.split(' ');
                strEndHour = endDateHour[0]; 
                strEndHour = parseInt(strEndHour) + 12; 
            }
            timeEnd.setHours(strEndHour, endDateMinute, 0, 0);
            if (timeStart < timeEnd) {
                args.IsValid = true;

            }
            else {
                args.IsValid = false;
            }
        }