JS日期:根据出生日期 得到周岁年龄

//JS日期系列：根据出生日期 得到周岁年龄              
//参数strBirthday已经是正确格式的2007.02.09这样的日期字符串
//后续再增加相关的如日期判断等JS关于日期处理的相关方法
function jsGetAge(strBirthday)
{      
    var returnAge;
    var strBirthdayArr=strBirthday.split(".");
    var birthYear = strBirthdayArr[0];
    var birthMonth = strBirthdayArr[1];
    var birthDay = strBirthdayArr[2];
   
    d = new Date();
    var nowYear = d.getYear();
    var nowMonth = d.getMonth() + 1;
    var nowDay = d.getDate();
   
    if(nowYear == birthYear)
    {
        returnAge = 0;//同年 则为0岁
    }
    else
    {
        var ageDiff = nowYear - birthYear ; //年之差
        if(ageDiff > 0)
        {
            if(nowMonth == birthMonth)
            {
                var dayDiff = nowDay - birthDay;//日之差
                if(dayDiff < 0)
                {
                    returnAge = ageDiff - 1;
                }
                else
                {
                    returnAge = ageDiff ;
                }
            }
            else
            {
                var monthDiff = nowMonth - birthMonth;//月之差
                if(monthDiff < 0)
                {
                    returnAge = ageDiff - 1;
                }
                else
                {
                    returnAge = ageDiff ;
                }
            }
        }
        else
        {
            returnAge = -1;//返回-1 表示出生日期输入错误 晚于今天
        }
    }
   
    return returnAge;//返回周岁年龄
   
}