Simple Game Engine in JavaScript

I’m planning on creating a Mortal Kombat-inspired game in JavaScript. I’ve written a basic game engine that manages my game states and creates a game loop.

I just wondered if it could be improved at all? As I’m a web developer by trade and this is my first foray into programming games.

/**
 * Game engine.
 */
function GameEngine() {
    this.states = new Array();
    this.currentState;
    this.running = false;
};

GameEngine.prototype.init = function() {
    this.running = true;
};

GameEngine.prototype.changeState = function(state) {
    this.currentState = state;
};

GameEngine.prototype.isRunning = function() {
    return this.running;
};

GameEngine.prototype.handleEvents = function() {
    this.currentState.handleEvents(this);
};

GameEngine.prototype.update = function() {
    this.currentState.update(this);
};

GameEngine.prototype.draw = function() {
    this.currentState.draw(this);
};

/**
 * Base game state state.
 */
function GameState() {};

/**
 * Intro state.
 */
function IntroState() {};

IntroState.prototype = Object.create(GameState.prototype);

IntroState.prototype.handleEvents = function(game) {
    console.log('IntroState::handleEvents');
};

IntroState.prototype.update = function(game) {
    console.log('IntroState::update');
};

IntroState.prototype.draw = function(game) {
    console.log('IntroState::draw');
};

/**
 * Initialises the game.
 */
(function() {
    var game = new GameEngine();
    var gameLoop;
    var frameLength = 500;

    game.init();
    game.changeState(new IntroState());

    gameLoop = setInterval(function() {
        game.handleEvents();
        game.update();
        game.draw();
    }, frameLength);
})();

There's really not much to say about this code, so I'll quote a comment posted on this question:


[...] a basic game engine is a loop and a redraw/update system. So yes you are good. You should explore other game engines in javascript and see what they do. – Steven

Just one thing that's itching: you're declaring var frameLength = 500; - I think this is going to bite you later, when you want to adjust frame rate (FPS).

StackExchange Code Review Q#31901, answer score: 2