Javascript运行时错误：应用程序未定义

我正在尝试使用画布和Javascript为我正在制作的Windows8应用程序制作一个基本的应用程序。在Visual Studio 2012中为windows 8应用程序编译代码时，我收到以下消息

0x800a1391-JavaScript运行时错误：“应用程序”未定义

我做错了什么？我应该使用什么代码来修复问题

HTML

---

另外，我在使用CreateJS，如果这意味着任何东西

app

不是全局的，那么在上面的上下文中确实是未定义的。它在

default.js

中的模块（匿名函数）中定义：

(function () {
    "use strict";

    WinJS.Binding.optimizeBindingReferences = true;

    var app = WinJS.Application;

也就是说，在这段代码中你想做什么？将包括代码，以在您的应用程序暂停时保持状态；在这种情况下，添加事件侦听器并调用

start

并没有真正意义

var canvas, content, stage;
var bgimage, b1Image, p2Image, ammoImage, p1Lives, p2Lives, title, endGameImage;
var bgbitmap, p1bitmap, p2bitmap, ammoBitmap;
var preload;

// Scale Factor
var SCALE_X = window.innerWidth / 800;
var SCALE_Y = window.innerHeight / 480;
var MARGIN = 25;
var GROUND_Y = 390 * SCALE_Y;


function initialize() {
    canvas = document.getElementById("gameCanvas");
    canvas.width = window.innWidth
    canvas.height = window.innerHeight;
    context = canvas.getContext("2d");

    function prepareGame() {
        bgimage = preload.getResult("screenImage").result;
        bgbitmap = new Bitmap(bgimage);
        bgbitmap.scaleX = SCALE_X
        bgbitmap.scaleY = SCALE_Y
        stage.addChild(bgBitmap);

        stage.update();
    }

    //PreloadJS
    preload = new PreloadJS();
    preload.onComplete = prepareGame;
    var manifest = [
    { id: "screenImage", src: "images/Backgrounds/gameplay_screen.png" },
    { id: "redImage", src: "images/Catapults/Red/redIdle/redIdle.png" },
{ id: "blueImage", src: "images/Catapluts/Blue/blueIdle/blueIdle.png" },
{ id: "ammoImage", src: "images/Ammo/rock_ammo.png" },
{ id: "winImage", src: "images/Backgrounds/victory.png" },
{ id: "loseImage", src: "images/Backgrounds/defeat.png"  },
{ id: "blueFire", src: "images/Catapults/Blue/blueFire/blueCatapult_fire.png" },
{ id: "redFire", src: "images/catapults/Red/redFire/redCatapult_fire.png" }
];
preload.loadManifest(manifest);

stage = new Stage(canvas);
}

function gameLoop() {
    update();
    draw();
}

function update() {

}

function draw() {

}

app.oncheckpoint = function  (args) { 
    document.addEventListener("DOMContentLoaded", initialize, false);
    app.start();
};

(function () {
    "use strict";

    WinJS.Binding.optimizeBindingReferences = true;

    var app = WinJS.Application;