date.js

function parseAge(dateString) {
    function parse(date) {
        date = date || '00/00/0000';
        var dateStorage = date.split('/');
        return dateStorage[1].replace(/^0/, '') + '/' + dateStorage[0] + '/' + dateStorage[2];
    }
    var today = new Date();
    var birthDate = new Date(parse(dateString));
    var age = today.getFullYear() - birthDate.getFullYear();
    var m = today.getMonth() - birthDate.getMonth();
    if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
        age--;
    }
    return age;
};

if (parseAge('17/06/1993') >= 18) {
        return true;
    } else {
        return false;
}