Objects

var freddie = {
    firstName:  "Farrokh",
    surname:    "Bulsara",
    hobbies:    ["stamp collecting", "music"]
};

console.log( freddie.surname );  // Bulsara
freddie.dob = new Date(1946, 8, 5);
freddie.dobISO = function() {
    return this.dob.toISOString();
}
console.log( freddie.dobISO() );