//Get 1 day in milliseconds
var one_day=1000*60*60*24

var today=new Date();

function calc_years(b_year,b_month,b_day) {

    var birthday = new Date(b_year,b_month,b_day);

    return Math.floor(((today.getTime() - birthday.getTime()) / one_day) / 365);
}

function calc_days(b_year,b_month,b_day,years) {

    var bday_thisyear = new Date(b_year + years,b_month,b_day);

    return Math.floor((today.getTime() - bday_thisyear.getTime()) / one_day);
}

function calc(b_year,b_month,b_day) {

    b_month -= 1; //Month is 0-11 in JavaScript

    var years = calc_years(b_year,b_month,b_day);
    var days  = calc_days(b_year,b_month,b_day,years);

    var res = "";
    if ( years > 0)  res += years +" éves ";
    if ( days > 0)   res += days  +" napos";

    if (res == "") res = "számolási hiba";
    
    return res;
}

function kora(id,b_year,b_month,b_day) {

    document.getElementById(id).innerHTML = calc(b_year,b_month,b_day);
    
}

kora("anna",1997,12,23);
kora("eva",1995,9,24);
kora("laci",1968,5,1);