Node.js Blackjack using the Prototype and Constructor Approach

blackjack.js

var readline = require('readline').createInterface({
	input: process.stdin,
	output: process.stdout
});


// CARD CLASS
var Card = function(face, suite) {
	if (this.faces.indexOf(face) == -1) {
		throw new Error("Invalid Face: " + face);
	}

	if (this.suites.indexOf(suite) == -1) {
		throw new Error("Invalid Suite: " + suite);
	}

	this.face = face;
	this.suite = suite;
};

Card.prototype.faces = [ 'A', '2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K' ];

Card.prototype.suites = [ 'Hearts', 'Spades', 'Diamonds', 'Clubs' ];


// CARD COLLECTION CLASS
var CardCollection = function() {
	this.cards = []; // Array of Card instances
};


// HAND CLASS
var Hand = function() { };

Hand.prototype = new CardCollection();
Hand.prototype.constructor = Hand;

Hand.prototype.limit = 21;

Hand.prototype.add = function(card) {
	if (!card instanceof Card) {
		throw new Error("Tried adding a non card to hand!");
	}

	this.cards.push(card);
};

Hand.prototype.score = function() {
	var score = 0, aces = 0;

	this.cards.forEach(function(card) {
		if (card.face == 'A') {
			aces++;
		}

		if (card.face == 'J' || card.face == 'Q' || card.face == 'K') {
			score += 10;
		} else if (card.face == 'A') { // Optimistically assume high values for aces
			score += 11;
		} else {
			score += parseInt(card.face, 10);
		}
	});

	while (score > 21 && aces > 0) {
		score -= 10;
		aces --;
	}

	return score;
};


Hand.prototype.toString = function() {
	console.log("Your Hand:");

	this.cards.forEach(function(card) {
		console.log("  " + card.face + " of " + card.suite);
	});

	console.log("Total Points: " + this.score() + "\n");
};

Hand.prototype.bust = function() {
	return this.score() > this.limit;
};


// DECK CLASS
var Deck = function() {
	var self = this;

	Card.prototype.suites.forEach(function(suite) {
		Card.prototype.faces.forEach(function(face) {
			self.cards.push(new Card(face, suite));
		});
	});
};

Deck.prototype = new CardCollection();
Deck.prototype.constructor = Deck;

Deck.prototype.draw = function() {
	return this.cards.pop();
};

Deck.prototype.shuffle = function() {
	for (var j, x, i = this.cards.length; i; j = Math.floor(Math.random() * i), x = this.cards[--i], this.cards[i] = this.cards[j], this.cards[j] = x);
};


// PROCEDURAL GAME CODE
var deck = new Deck();
deck.shuffle();

var player1 = new Hand();

player1.add(deck.draw());
player1.add(deck.draw());

var play = function() {
	console.log(player1.toString());

	readline.question("[H]it or [S]tay? ", function(answer) {
		if (answer == 'h' || answer == 'H') {
			player1.add(deck.draw());

			if (player1.bust()) {
				console.log("BUST!");
				console.log(player1.toString());
				readline.close();
			} else {
				console.log("HITTING!");
				play();
			}
		} else if (answer == 's' || answer == 'S') {
			console.log("STAYING!");
			console.log(player1.toString());
			readline.close();
		}
	});
}

play();