Find Age from Month/Day/Year

gistfile1.js

function displayage( yr, mon, day, unit, decimal, round ) {
	//Sample usage
	//displayage (year, month, day, unit, decimals, rounding)
	//Unit can be "years", "months", or "days"
	//Decimals specifies demical places to round to (ie: 2)
	//Rounding can be "roundup" or "rounddown"
	//displayage(1997, 11, 24, "years", 0, "rounddown")
	
	today = new Date();
	yr = parseInt(yr, 10);
	mon = parseInt(mon, 10);
	day = parseInt(day, 10);
	var one_day = 1000*60*60*24;
	var one_month = 1000*60*60*24*30;
	var one_year = 1000*60*60*24*30*12;
	var pastdate = new Date(yr, mon-1, day);
	var countunit = unit;
	var decimals = decimal;
	var rounding = round;
	var return_value = 0;
	finalunit = ( countunit == "days" ) ? one_day : ( countunit == "months" ) ? one_month : one_year;
	decimals = ( decimals <= 0 ) ? 1 : decimals * 10;
	
	if ( unit != "years" ) {
		if ( rounding == "rounddown" )
			return_value = Math.floor ( ( today.getTime() - pastdate.getTime() ) / ( finalunit ) * decimals ) / decimals;
		else
			return_value = Math.ceil ( ( today.getTime() - pastdate.getTime() ) / ( finalunit ) * decimals ) / decimals;
	} else {
		yearspast = today.getFullYear()-yr-1;
		tail = ( today.getMonth() > mon - 1 || today.getMonth() == mon - 1 && today.getDate() >= day ) ? 1 : 0;
		return_value = yearspast + tail;
	}
	
	return return_value;
}