我会选择可读性:

function _calculateAge(birthday) { // birthday is a date
    var ageDifMs = Date.now() - birthday.getTime();
    var ageDate = new Date(ageDifMs); // miliseconds from epoch
    return Math.abs(ageDate.getUTCFullYear() - 1970);
}

免责声明:这也有精度问题，所以这也不能完全信任。它可以关闭几个小时，几年，或在夏令时(取决于时区)。

相反，如果精度非常重要，我建议使用一个库。还有@Naveens的帖子，可能是最准确的，因为它不依赖于一天中的时间。

let dt = dob;

        let age = '';

        let bY = Number(moment(dt).format('YYYY')); 
        let bM = Number(moment(dt).format('MM')); 
        let bD = Number(moment(dt).format('DD')); 

        let tY = Number(moment().format('YYYY')); 
        let tM = Number(moment().format('MM')); 
        let tD = Number(moment().format('DD')); 


        age += (tY - bY) + ' Y ';

        if (tM < bM) {
            age += (tM - bM + 12) + ' M ';
            tY = tY - 1;
        } else {
            age += (tM - bM) + ' M '
        }

        if (tD < bD) {
            age += (tD - bD + 30) + ' D ';
            tM = tM - 1;
        } else {
            age += (tD - bD) + ' D '
        }
        
        //AGE MONTH DAYS
        console.log(age);

这个问题已经超过10年了，没有人回答过提示，他们已经有了YYYYMMDD格式的出生日期?

如果你有一个YYYYMMDD格式的过去日期和当前日期，你可以像这样快速计算它们之间的年数:

var pastDate = '20101030';
var currentDate = '20210622';
var years = Math.floor( ( currentDate - pastDate ) * 0.0001 );
// 10 (10.9592)

你可以得到当前日期格式为YYYYMMDD，如下所示:

var now = new Date();

var currentDate = [
    now.getFullYear(),
    ('0' + (now.getMonth() + 1) ).slice(-2),
    ('0' + now.getDate() ).slice(-2),
].join('');

以下是计算年龄的简单方法:

//dob date dd/mm/yy 
var d = 01/01/1990


//today
//date today string format 
var today = new Date(); // i.e wed 04 may 2016 15:12:09 GMT
//todays year
var todayYear = today.getFullYear();
// today month
var todayMonth = today.getMonth();
//today date
var todayDate = today.getDate();

//dob
//dob parsed as date format   
var dob = new Date(d);
// dob year
var dobYear = dob.getFullYear();
// dob month
var dobMonth = dob.getMonth();
//dob date
var dobDate = dob.getDate();

var yearsDiff = todayYear - dobYear ;
var age;

if ( todayMonth < dobMonth ) 
 { 
  age = yearsDiff - 1; 
 }
else if ( todayMonth > dobMonth ) 
 {
  age = yearsDiff ; 
 }

else //if today month = dob month
 { if ( todayDate < dobDate ) 
  {
   age = yearsDiff - 1;
  }
    else 
    {
     age = yearsDiff;
    }
 }

moment.js还有一个可能的解决方案:

var moment = require('moment');
var startDate = new Date();
var endDate = new Date();
endDate.setDate(endDate.getFullYear() + 5); // Add 5 years to second date
console.log(moment.duration(endDate - startDate).years()); // This should returns 5

这对我来说是最优雅的方式:

const getAge = (birthDateString) => { const today = new Date(); const birthDate = new Date(birthDateString); const yearsDifference = today.getFullYear() - birthDate.getFullYear(); 如果( 今天。getmonth () < birthDate.getMonth() || . getmonth ( (today.getMonth() === birthDate.getMonth() && today.getDate() < birthDate.getDate())) ) { 返回yearsDifference - 1; ｝ 返回yearsDifference; }; console.log (getAge (' 2018-03-12 '));