如何ActionScript3 根据出生日期获得年龄

我一直很诧异，居然不能很容易的找到ActionScript3 根据出生日期获得年龄的代码。
最后在drawlogic找到，发现他和我发出了一样的感慨。

function calculateAge(birthdate:Date):Number {
    var dtNow:Date = new Date();// gets current date
    var currentMonth:Number = dtNow.getMonth();
    var currentDay:Number = dtNow.getDay();
    var currentYear:Number = dtNow.getFullYear();

    var bdMonth:Number = birthdate.getMonth();
    var bdDay:Number = birthdate.getDay();
    var bdYear:Number = birthdate.getFullYear();

    // get the difference in years
    var years:Number = dtNow.getFullYear() - birthdate.getFullYear();
    // subtract another year if we're before the
    // birth day in the current year
    if (currentMonth < bdMonth || (currentMonth == bdMonth && currentDay < bdDay)) {
        years--;
    }
    return years;
}

function dateStringToObject(dateString):Date {
    var date_ar = dateString.split("/");
    return new Date(date_ar[2],date_ar[0] - 1,date_ar[1]);
}

var dateNow:Date = new Date();
var checkDate:String = "10/22/1987";
var dateBirthday:Date = dateStringToObject(checkDate);
trace("dateNow = "+dateNow);
trace("dateBirthday = "+dateBirthday);
trace("age = "+calculateAge(dateBirthday));

IT'S NEAL MI.