Custom Validation for Date of Birth using three dropdownlist

This article is used to validate the date of birth having 3 dropdownlist control.first dropdownlist control populates data for Days second for Months and third for Years.this article is exactly usefull for the users those want to validate DOB containing three dropdownlist.Datasources for Days and Months populates from two XML Files(DD.xml and MM.xml) in this project.

Creatinng two xml files for Days and Months where thease will be used as a datasource to bind the dropdownlist controls for days and months only

<?xml version="1.0" encoding="UTF-8" ?>

following javascript snippet is incorrect: 

         if(DobMonth % 2==0 && DobDate=="31")
        {
         args.IsValid = false;
         return;
        }

For instance December does have 31 days althought 12 % 2 is 0...

to fix it:

#1) I replaced the function "isleap( )" with the following one which does a bit more work:

function MonthsLastDay(year,month){
    if (month==2)
         return ((year % 4 == 0) && ( (year % 100 != 0) || (year % 400 == 0))) ? 29 : 28;
    return (month==4 || month==6 || month==9 || month==11) ? 30 : 31;
}

#2) I replaced the part which was doing the day-of-the-month check with: 

if (date_DOB_Day > MonthsLastDay(date_DOB_Year, date_DOB_Month)) {
    arguments.IsValid=false;
    return;
}