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我正在構建我的第一個迷你JS遊戲,並通過w3schools教程工作,但無法在codepen預覽區域加載我的第一個組件。這是一個非常令人失望的前幾步。我知道myGameArea加載正常,因爲它的風格流行,但我只想要一個簡單的紅色方塊來繪製它的頂部。如何用Javascript繪製畫布
var myGamePiece;
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120);
myGameArea.start();
}
var myGameArea = {
canvas: document.createElement("canvas"),
start: function() {
this.canvas.width = 480;
this.canvas.height = 270;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
},
clear: function(){
this.context.clearRect(0,0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y) {
this.width = width;
this.height = height;
this.x = x;
this.y = y;
this.update = function(){
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
function updateGameArea() {
myGameArea.clear();
myGameArea.update();
}
<button onClick="startGame()">
Press
</button>
您是否在控制檯中發現任何錯誤? – dan08
你似乎沒有定義'myGameArea.update()' –
你的意思是'myGamePiece.update()'? –