Scene management, loading assets, beginning a game loop

GameScene.js

var Client = require('../Client')

function GameScene() {
    this.client = new Client()    
}

GameScene.prototype.enterScene = function() {
    console.log('GameScene entered')
    this.client.connect()
}


GameScene.prototype.update = function(delta, tick, now) {
    // call the game client's update each tick
    this.client.update(delta, tick, now)
}


module.exports = GameScene

LoadingScene.js

var GameScene = require('./GameScene')

function LoadingScene() {
    // TODO load more stuffz? all this game needs so far is a sprite sheet
}

LoadingScene.prototype.enterScene = function() {
    /* I would display a loading screen but everything loads so quickly */
    PIXI.SCALE_MODES.DEFAULT = PIXI.SCALE_MODES.NEAREST
    PIXI.loader.add('spritesheet', '/images/spritesheet.json')
    PIXI.loader.load((loader, resource) => {
        console.log('spritesheet loaded')  
        // start the game
        this.sceneManager.gotoScene(new GameScene())
    })
}

module.exports = LoadingScene

main.js

var SceneManager = require('../../game/client/scene/SceneManager')
var LoadingScene = require('../../game/client/scene/LoadingScene')

var scenes = new SceneManager()

window.onload = function() {
    console.log('window loaded')
    scenes.gotoScene(new LoadingScene()
    var loop = function() {
        scenes.update()
        window.requestAnimationFrame(loop)
    }

    loop()
}

SceneManager.js

function SceneManager() {
    this.currentScene = null
}

SceneManager.prototype.gotoScene = function(scene) {
    if (this.currentScene) {
        if (typeof this.currentScene.exitScene === 'function') {
            this.currentScene.exitScene()
        }        
    }

    this.currentScene = scene
    scene.sceneManager = this
    scene.enterScene()
}

var prev = Date.now()
var now = Date.now()
var tick = 0
SceneManager.prototype.update = function() {
    now = Date.now()

    var deltaTime = (now - prev) / 1000
    prev = now

    if (this.currentScene) {
        if (typeof this.currentScene.update === 'function') {
            this.currentScene.update(deltaTime, tick, now)
        }
    }
    tick++
}

module.exports = SceneManager