我正在开发一款适用于 Windows 8 的 HTML5 和 JavaScript 游戏。我有一个将“roach”对象存储在数组中的游戏的工作版本。我正在尝试将我拥有的游戏代码放入 Microsoft 的示例中（在此处链接）。在这个例子中，他们为游戏状态声明了一组对象字面量，这些字面量被保存并在各种类中使用：
internal: {
gamePaused: false,
gamePhase: "ready",
speed: 5,
score: 0,
}
在那里，我想为我的 roach 对象放置数组。我以为我可以这样做：
roaches: [],
但是当我打电话时：
this.state.roaches.push(new Roach());
this.state.roaches.length;
我得到一个：
JavaScript runtime error: Unable to get property 'length' of undefined or null reference
我做错了什么，我该如何解决？
纳特
附加信息：
好吧，这是我的蟑螂课：
var Roach = WinJS.Class.define( function () {
this.position.x = Math.random() * gameCanvas.width + 1;
this.position.y = Math.random() * gameCanvas.height + 1;
this.squished = false;
this.image = GameManager.assetManager.assets.roachImage;
},
{
move: function (speed) {
// changes position
},
squish: function() {
}
});
这是在一个名为 game.js 的文件中，其中包含另一个类：
var Game = WinJS.Class.define(
null,
{
// other functions
// Called when the game is being prepared to start
ready: function () {
// TODO: Replace with your own new game initialization logic
if (this.isSnapped()) {
this.state.gamePaused = true;
} else {
this.state.gamePaused = false;
}
this.state.gamePhase = "ready";
switch (this.settings.skillLevel) {
case 0:
this.state.speed = 3;
break;
case 1:
this.state.speed = 5;
break;
case 2:
this.state.speed = 10;
break;
}
this.state.roaches.push(new Roach());
this.state.score = 0;
},
// Main game render loop
draw: function () {
this.gameContext.clearRect(0, 0, gameCanvas.width, gameCanvas.height);
// TODO: Sample game rendering to be replaced
// Draw the current score
this.gameContext.fillStyle = "#FFFF99";
this.gameContext.font = "bold 48px Segoe UI";
this.gameContext.textBaseline = "middle";
this.gameContext.textAlign = "right";
this.gameContext.fillText(this.state.score, gameCanvas.width - 5, 20);
// update image positions
// THROWS ERROR HERE
for (var i = 0; i < this.state.roaches.length; i++) {
if (!this.state.roaches[i].squished) {
}
}
// Draw a ready or game over or paused indicator
if (this.state.gamePhase === "ready") {
this.gameContext.textAlign = "center";
this.gameContext.fillText("READY", gameCanvas.width / 2, gameCanvas.height / 2);
} else if (this.state.gamePhase === "ended") {
this.gameContext.textAlign = "center";
this.gameContext.fillText("GAME OVER", gameCanvas.width / 2, gameCanvas.height / 2);
} else if (this.state.gamePaused) {
this.gameContext.textAlign = "center";
this.gameContext.fillText("PAUSED", gameCanvas.width / 2, gameCanvas.height / 2);
}
}
现在在一个名为 gameState.js 的文件中定义了一个 gameState 类，其中包含我之前引用的变量。
var GameState = WinJS.Class.define(
null,
{
config: {
// TODO: Adjust these values to configure the template itself
frameRate: 20, // Set to 0 to have no update loop at all
minSquished: 20,
currentPage: "/html/homePage.html",
gameName: "SDK Game Sample", // Used by share contract on scores page
},
// TODO: Replace these public settings exposed on the settings panel
external: {
playerName: "Player",
soundVolume: 100,
skillLevel: 0,
},
// TODO: Replace these values with state variables relevant for your game
internal: {
gamePaused: false,
gamePhase: "ready",
roaches: [],
speed: 5,
score: 0,
},
这些文件在 GameManager 命名空间下组装，该命名空间从文件中调用每个类并在该命名空间下创建它们。因此，当用户开始游戏时，GameManager 会调用 ready 函数，然后调用 draw 函数来更新屏幕。希望这有助于澄清。
命名空间在这里定义：
var game = new Game();
var touchPanel = new TouchPanel();
var state = new GameState();
state.load();
WinJS.Namespace.define("GameManager", {
navigateHome: navigateHome,
navigateGame: navigateGame,
navigateRules: navigateRules,
navigateScores: navigateScores,
navigateCredits: navigateCredits,
showPreferences: showPreferences,
onBeforeShow: onBeforeShow,
onAfterHide: onAfterHide,
game: game,
state: state,
assetManager: assetManager,
scoreHelper: scoreHelper,
gameId: gameId,
touchPanel: touchPanel
});