js使用出生日期计算年龄

function calcAge(dateText)
{
var birthday=new Date(dateText.replace(/-/g, "/"));
var d=new Date();
var age = d.getFullYear()-birthday.getFullYear()-((d.getMonth()<birthday.getMonth()|| d.getMonth()==birthday.getMonth() && d.getDate()<birthday.getDate())?1:0);
var month = calculateMonth(dateText);
var year = calculateAge(dateText);
document.all.item("ageTextField").value=age;
if(year >= 0){
if(month<0 && year==1){
 document.all.item("ageTextField").value='0';
 }
 else{
document.all.item("ageTextField").value=year;
}
}
else{
document.all.item("ageTextField").value="";
}
}
//根据出生日期计算年龄
function calculateMonth(birthday)
{
var month=-1;
 if(checkBirthday(birthday))
{
var aDate=birthday.split("-");
if(aDate[1].substr(0,1) == '0')
aDate[1]=aDate[1].substring(1);
var birthdayMonth = parseInt(aDate[1]);
var currentDate = new Date();
    var currentMonth = parseInt(currentDate.getMonth()+1);
    month = currentMonth-birthdayMonth;
    return month;
}
 return month;
}

function calculateAge(birthday){
if(checkBirthday(birthday)){
var aDate=birthday.split("-");
var birthdayYear = parseInt(aDate[0]);
var currentDate = new Date();
    var currentYear = parseInt(currentDate.getFullYear());
    return currentYear-birthdayYear;
    }
    return 0;
}