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 '));

使用ES6的干净的一行程序解决方案:

const getAge = birthDate => Math.floor((new Date() - new Date(birthDate).getTime()) / 3.15576e+10)

// today is 2018-06-13
getAge('1994-06-14') // 23
getAge('1994-06-13') // 24

我使用的是365.25天的一年(因为闰年是0.25天)，分别是3.15576e+10毫秒(365.25 * 24 * 60 * 60 * 1000)。

它有几个小时的剩余时间，所以根据用例，它可能不是最佳选择。

function age()
{
    var birthdate = $j('#birthDate').val(); // in   "mm/dd/yyyy" format
    var senddate = $j('#expireDate').val(); // in   "mm/dd/yyyy" format
    var x = birthdate.split("/");    
    var y = senddate.split("/");
    var bdays = x[1];
    var bmonths = x[0];
    var byear = x[2];
    //alert(bdays);
    var sdays = y[1];
    var smonths = y[0];
    var syear = y[2];
    //alert(sdays);

    if(sdays < bdays)
    {
        sdays = parseInt(sdays) + 30;
        smonths = parseInt(smonths) - 1;
        //alert(sdays);
        var fdays = sdays - bdays;
        //alert(fdays);
    }
    else{
        var fdays = sdays - bdays;
    }

    if(smonths < bmonths)
    {
        smonths = parseInt(smonths) + 12;
        syear = syear - 1;
        var fmonths = smonths - bmonths;
    }
    else
    {
        var fmonths = smonths - bmonths;
    }

    var fyear = syear - byear;
    document.getElementById('patientAge').value = fyear+' years '+fmonths+' months '+fdays+' days';
}

还有两个选择:

// Int Age to Date as string YYY-mm-dd
function age_to_date(age)
{
    try {
        var d = new Date();
        var new_d = '';
        d.setFullYear(d.getFullYear() - Math.abs(age));
        new_d = d.getFullYear() + '-' + d.getMonth() + '-' + d.getDate();

        return new_d;
    } catch(err) {
        console.log(err.message);
    }
}
// Date string (YYY-mm-dd) to Int age (years old)
function date_to_age(date)
{
    try {
        var today = new Date();
        var d = new Date(date);

        var year = today.getFullYear() - d.getFullYear();
        var month = today.getMonth() - d.getMonth();
        var day = today.getDate() - d.getDate();
        var carry = 0;

        if (year < 0)
            return 0;
        if (month <= 0 && day <= 0)
            carry -= 1;

        var age = parseInt(year);
        age += carry;

        return Math.abs(age);
    } catch(err) {
        console.log(err.message);
    }
}

看这个例子，你从这里得到完整的年、月、日信息

function getAge(dateString) {
    var today = new Date();
    var birthDate = new Date(dateString);
    var age = today.getFullYear() - birthDate.getFullYear();
    var m = today.getMonth() - birthDate.getMonth();
    var da = today.getDate() - birthDate.getDate();
    if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
        age--;
    }
    if(m<0){
        m +=12;
    }
    if(da<0){
        da +=30;
    }
    return age+" years "+ Math.abs(m) + "months"+ Math.abs(da) + " days";
}
alert('age: ' + getAge("1987/08/31"));    
[http://jsfiddle.net/tapos00/2g70ue5y/][1]

$("#birthday").change(function (){


var val=this.value;

var current_year=new Date().getFullYear();
if(val!=null){
    var Split = val.split("-");
    var birth_year=parseInt(Split[2]);

    if(parseInt(current_year)-parseInt(birth_year)<parseInt(18)){

  $("#maritial_status").attr('disabled', 'disabled');
        var val2= document.getElementById("maritial_status");
        val2.value = "Not Married";
        $("#anniversary").attr('disabled', 'disabled');
        var val1= document.getElementById("anniversary");
        val1.value = "NA";

    }else{
        $("#maritial_status").attr('disabled', false);
        $("#anniversary").attr('disabled', false);

    }
}
});