// JavaScript Document
//Prevents impossible dates (e.g. February 31st)
function correctdays(month,day,year)
{
	var selected_month = document.getElementById(month).selectedIndex;
	selected_month = document.getElementById(month).options[selected_month].value;
	
	//If the selected month is February
	if(selected_month == 2)
	{		
		var selected_year = document.getElementById(year).selectedIndex;
		selected_year = document.getElementById(year).options[selected_year].value;

		if(selected_year % 4 == 0)
		{
			var days_in_feb = 29;
		}
		else
		{
			var days_in_feb = 28;
		}

		if(days_in_feb == 29 && document.getElementById(day).length == 28)
		{
			var newday = document.createElement('option');
			newday.text = 29;
			newday.value = 29;
			
			//Code in catch block for IE
			try
			{
				document.getElementById(day).add(newday,null);
			}
			catch(e)
			{					
				document.getElementById(day).add(newday);
			}
		}
		else
		{
			for(var i = document.getElementById(day).length; i > days_in_feb; --i)
			{
				document.getElementById(day).remove((i - 1))
			}
		}
	}

	//If the selected month should have 30 days
	else if(selected_month == 4 || selected_month == 6 || selected_month == 9 || selected_month == 11)
	{

		if(document.getElementById(day).length == 31)
		{
			document.getElementById(day).remove(30);
		}

		else if(document.getElementById(day).length < 30)
		{
			for(var i = document.getElementById(day).length + 1; i <= 30; ++i)
			{
				var newday = document.createElement('option');
				newday.text = i;
				newday.value = i;
				document.getElementById(day).add(newday,null);
			}
		}	
	}

	//If the selected month should have 31 days
	else
	{
		for(var i = document.getElementById(day).length + 1; i <= 31; ++i)
		{
			var newday = document.createElement('option');
			newday.text = i;
			newday.value = i;
			document.getElementById(day).add(newday,null);
		}
	}
}