計算年齡大小

function calculateAge(startDate,endDate){
var age = 0;
if(startDate != '' && endDate != '') {
var start = new Date(startDate.split('/')[2]+'/'+startDate.split('/')[1]+'/'+startDate.split('/')[0]);
var end = new Date(endDate.split('/')[2] + '/' + endDate.split('/')[1] + '/' + endDate.split('/')[0]);

var starty = start.getFullYear();
var startm = start.getMonth() + 1;
var startd = start.getDate();

var endy = end.getFullYear();
var endm = end.getMonth() + 1;
var endd = end.getDate();

if (endy - starty < 0) {
alert("Input Error!");
age = "";
} else {
if (endm - startm < 0) {
age = endy - starty - 1;
} else {
if (endd - startd >= 0) {
age = endy - starty;
} else {
age = endy - starty - 1;
}
}
}
if(age < 0) {
age = 0;
}
return age;
}
}