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;
    }
 }

还有另一个解决方案:

/**
 * Calculate age by birth date.
 *
 * @param int birthYear Year as YYYY.
 * @param int birthMonth Month as number from 1 to 12.
 * @param int birthDay Day as number from 1 to 31.
 * @return int
 */
function getAge(birthYear, birthMonth, birthDay) {
  var today = new Date();
  var birthDate = new Date(birthYear, birthMonth-1, birthDay);
  var age = today.getFullYear() - birthDate.getFullYear();
  var m = today.getMonth() - birthDate.getMonth();
  if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
    age--;
  }
  return age;
}

momentjs:

/* The difference, in years, between NOW and 2012-05-07 */
moment().diff(moment('20120507', 'YYYYMMDD'), 'years')

$("#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);

    }
}
});

使用javascript从出生日期获取年龄(年，月和日)

函数calcularEdad(年，月和日)

function calcularEdad(fecha) {
        // Si la fecha es correcta, calculamos la edad

        if (typeof fecha != "string" && fecha && esNumero(fecha.getTime())) {
            fecha = formatDate(fecha, "yyyy-MM-dd");
        }

        var values = fecha.split("-");
        var dia = values[2];
        var mes = values[1];
        var ano = values[0];

        // cogemos los valores actuales
        var fecha_hoy = new Date();
        var ahora_ano = fecha_hoy.getYear();
        var ahora_mes = fecha_hoy.getMonth() + 1;
        var ahora_dia = fecha_hoy.getDate();

        // realizamos el calculo
        var edad = (ahora_ano + 1900) - ano;
        if (ahora_mes < mes) {
            edad--;
        }
        if ((mes == ahora_mes) && (ahora_dia < dia)) {
            edad--;
        }
        if (edad > 1900) {
            edad -= 1900;
        }

        // calculamos los meses
        var meses = 0;

        if (ahora_mes > mes && dia > ahora_dia)
            meses = ahora_mes - mes - 1;
        else if (ahora_mes > mes)
            meses = ahora_mes - mes
        if (ahora_mes < mes && dia < ahora_dia)
            meses = 12 - (mes - ahora_mes);
        else if (ahora_mes < mes)
            meses = 12 - (mes - ahora_mes + 1);
        if (ahora_mes == mes && dia > ahora_dia)
            meses = 11;

        // calculamos los dias
        var dias = 0;
        if (ahora_dia > dia)
            dias = ahora_dia - dia;
        if (ahora_dia < dia) {
            ultimoDiaMes = new Date(ahora_ano, ahora_mes - 1, 0);
            dias = ultimoDiaMes.getDate() - (dia - ahora_dia);
        }

        return edad + " años, " + meses + " meses y " + dias + " días";
    }

函数esNumero

function esNumero(strNumber) {
    if (strNumber == null) return false;
    if (strNumber == undefined) return false;
    if (typeof strNumber === "number" && !isNaN(strNumber)) return true;
    if (strNumber == "") return false;
    if (strNumber === "") return false;
    var psInt, psFloat;
    psInt = parseInt(strNumber);
    psFloat = parseFloat(strNumber);
    return !isNaN(strNumber) && !isNaN(psFloat);
}

我有点晚了，但我发现这是计算出生日期的最简单的方法。

希望这能有所帮助。

function init() { writeYears("myage", 0, Age()); } function Age() { var birthday = new Date(1997, 02, 01), //Year, month-1 , day. today = new Date(), one_year = 1000 * 60 * 60 * 24 * 365; return Math.floor((today.getTime() - birthday.getTime()) / one_year); } function writeYears(id, current, maximum) { document.getElementById(id).innerHTML = current; if (current < maximum) { setTimeout(function() { writeYears(id, ++current, maximum); }, Math.sin(current / maximum) * 200); } } init() <span id="myage"></span>