<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas { border:1px solid #d3d3d3;
background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
function startGame() { myGameArea.start();
myGamePiece = new component(30, 30, "red", 10, 120);
}
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);
window.addEventListener('keydown', function (e) { myGameArea.key = e.keyCode;
})
window.addEventListener('keyup', function (e) { myGameArea.key = false;
})
},
clear : function(){ this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y) { this.gamearea = myGameArea;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
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);
}
this.newPos = function() { this.x += this.speedX;
this.y += this.speedY;
}
}
function updateGameArea() { myGameArea.clear();
myGamePiece.speedX = 0;
myGamePiece.speedY = 0;
if (myGameArea.key && myGameArea.key == 37) {myGamePiece.speedX = -1; } if (myGameArea.key && myGameArea.key == 39) {myGamePiece.speedX = 1; } if (myGameArea.key && myGameArea.key == 38) {myGamePiece.speedY = -1; } if (myGameArea.key && myGameArea.key == 40) {myGamePiece.speedY = 1; } myGamePiece.newPos();
myGamePiece.update();
}
</script>
<p>确保该窗口获得焦点，然后您可以使用键盘上的箭头键移动红色方块。</p>
</body>
</html>