js通过出生日期获取周岁

<script type="text/javascript">
//1.函数;计算两个日期之间的天数。
var getOffDays = function(startDate, endDate) { 
    //得到时间戳相减 得到以毫秒为单位的差 
    var mmSec = (endDate.getTime() - startDate.getTime());
    //单位转换为天并返回
    return (mmSec / 3600000 / 24);
};

//2.获取当前时间
var now = new Date();
var year = now.getFullYear();
var month = now.getMonth()+1;
var day = now.getDate();

//3.获取出生日期
var birthday = "${each.birthday}";  //XXXX-XX-XX
var birth_year = birthday.substr(0,4);
var birth_month  = birthday.substr(5,2);
var birth_day  = birthday.substr(8,2);

//计算差额天数
var offDays = getOffDays(new Date(birth_year,birth_month,birth_day),
new Date(year,month,day));

//计算周岁
var age = parseInt(offDays /365);

</script>