Age Calculator

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css">
<input type="date"  class="span8"  name="birthdate" id="pick"  required=""  />
<div>Your Age: <span id="out">0</span></div>

JavaScript

function getAge(birthday) {
    var today = new Date();
    var thisYear = 0;
    if (today.getMonth() < birthday.getMonth()) {
        thisYear = 1;
    } else if ((today.getMonth() == birthday.getMonth()) && today.getDate() < birthday.getDate()) {
        thisYear = 1;
    }
    var age = today.getFullYear() - birthday.getFullYear() - thisYear;
    return age;
}

$('#pick').datepicker({
    onSelect: function(dateText, inst) {
        $('#out').html(getAge(new Date(dateText)));
    },
    maxDate: +0
});