Js计算年龄

计算年龄竟然还真的是个事

方法一, 找到今年的生日

function calculateAgeInYears (date) {
    var now = new Date();
    var year = now.getFullYear();
    var age = year - date.getFullYear();
    var birthday = new Date(year, date.getMonth(), date.getDate());
    return now >= birthday? age: age - 1;
}

方法二, 虽然很简洁, 但是, 可能构造出特殊情况会导致计算错误. 主要是因为这个答案把闰年搭进去了.

const getAge = birthDate => ~~((new Date() - new Date(birthDate).getTime()) / 31557600000)

方法三,

function getAge(dateString) {
    var today = new Date();
    var birthDate = new Date(dateString);
    var age = today.getFullYear() - birthDate.getFullYear();
    var m = today.getMonth() - birthDate.getMonth();
    if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
        age--;
    }
    return age;
}