Mediator

mediator.js

//part 1
function Player(name) {
    this.points = 0;
    this.name = name;
}
Player.prototype.play = function () {
    this.points += 1;
    mediator.played();
};
var scoreboard = {
    // HTML element to be updated
    element: document.getElementById('results'),
    // update the score display
    update: function (score) {
        // playing with DOM
    }
};

// part 2
var mediator = {
    // all the players
    players: {},
    // initialization
    setup: function () {
        var players = this.players;
        players.home = new Player('Home');
        players.guest = new Player('Guest');
    },
    // someone plays, update the score
    played: function () {
        var players = this.players,
        score = {
            Home: players.home.points,
            Guest: players.guest.points
        };
        scoreboard.update(score);
    },
    keypress: function (e) {
        e = e || window.event; // IE
        if (e.which === 49) { // key "1"
            mediator.players.home.play();
            return;
        }
        if (e.which === 48) { // key "0"
            mediator.players.guest.play();
            return;
        }
    }
};

//part 3
mediator.setup();
window.onkeypress = mediator.keypress;
// game over in 30 seconds
setTimeout(function () {
    window.onkeypress = null;
    alert('Game over!');
}, 30000);

Mediator

Wherefore
Mediator is a behavioral design pattern that allows us to expose a unified interface through which the different parts of a system may communicate.
Howto
Using additional object

Mediator. Pros/Cons

Advantages
weakens the relationship between objects
helps to simplify objects
Disadvantages
system is getting less transparent
performance degradation