javascriptのタイプミス
javascript初心者です。以下のコードでどこにミスがあるのか
解りません。どこにあるのでしょうか？ このソースをエディタに
貼ると見やすくなると思います。
<!DOCTYPE html>
<html>
<head>
<title>SnakeBite</title>
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<script type="text/javascript">
var W, H, S = 20;
var snake = [ ], foods = [ ];
var keyCode = 0;
var point = 0;
var timer = NaN;
var ctx;
// pointオブジェクト
function Point(x,y) {
this.x = x;
this.y = y;
}
//初期関数
function init() {
var canvas = document.getElementById('field');
W = canvas.width / S;
H = canvas.height / S;
ctx = canvas.getContext('2d');
ctx.font = "20px sans-serif";
//蚊の初期化
snake.push(new Point(W / 2, H / 2));
//餌の初期化
for (var i = 0 ; i < 10 ; i++) {
addFood();
}
timer = setInterval("tick()", 200);
window.onkeydown = keydown;
}
//餌の追加
function addFood() {
while (true) {
var x = Math.floor(Math.random() * W);
var y = Math.floor(Math.random() * H);
if (isHit(foods, x, y) || isHit(snake, x, y)) {
continue;
}
foods.push(new Point(x, y));
break;
}
}
//衝突判定
function isHit(data, x, y) {
for (var i = 0 ; i < data.length ; i++) {
if (data[i].x==x && data[i].y==Y) {
return true;
}
}
return false;
}
function moveFood(x, y) {
foods =foods. filter(function (p){return (p.x !=x || p.y !=y);}); addFood();
}
function tick() {
var x = snake[0].x;
var y = snake[0].y;
switch (keyCode) {
case 37: x--; break; //左
case 38: y--; break; //上
case 39: x++; break; //右
case 40: y++; break; //下
default: paint(); return;
}
//自分or壁に衝突
if(isHit(snake,x,y) || x<0 || x>=W || y<0 || y>=H )
clearInterval(timer);
paint();
return;
}
//頭を先頭に追加
snake.unshift(new Point(x,y));
if(isHit(foods, x, y)) {
point +=10; //餌を食べた
moveFood(x,y);
}else{
snake.pop(); //食べていない→しっぽを解除
}
paint();
}
function paint() {
ctx.clearRect(0,0,W * S, H * S);
ctx.fillStyle = "rgb(256,0,0)";
ctx.fillText(point, S, S * 2);
ctx.fillStyle = "rgb(0,0,255)";
foods.forEach(function (p) {
ctx.fillText("+", p.x * S, (p.y + 1) * S);});
snake.forEach(function (p) {
ctx.fillText("*", p.x * S, (p.y + 1) * S); });
}
function keydown(event) {
keyCode = event.keyCode;
}
</script>
</head>
<body onload="init()">
<canvas id="field" width="400" height="400" style="background:#cccccc">
</canvas>
</body>
</html>
