$(document).ready(function() {
	$("input[src$='http://www.brandleaders.com.au/www/372/files/button-signup.gif']").click(function() {
		if($('input[name=_1580_0]').val() != '')
		{
			if(calculateAge($('input[name=_1580_0]').val()) < 18)
			{
				alert('You must be over 18 years of age to join');
				return false;
			}
		}
	});
});

function calculateAge(input)
{
	var age;
	
	//var input = document.getElementById(inputFieldId).value;
	
	// Past date info
	var pyear = parseInt(input.substring(6,10));
	var pmonth = parseInt(input.substring(3,5),10) - 1;
	var pday = parseInt(input.substring(0,2),10);
	
	// Today info
	today = new Date();
	year = today.getFullYear() ;
	month = today.getMonth();
	day = today.getDate();

	if ( month < pmonth ){
		age = year - pyear - 1;
	}
	else if ( month > pmonth ){
		age = year - pyear;
	}
	else if ( month == pmonth ){
		if ( day < pday ){
			age = year - pyear - 1;
		}
		else if ( day > pday ){
			age = year - pyear;
		}
		else if ( day == pday ){
			age = year - pyear;
		}
	}
	return age;
}