Untitled

<!DOCTYPE HTML>

<html>
    <head>
        <title>Pastime</title>
    </head>
    <body>
		<canvas id="canvas">This text is displaying if your browser is unable to display HTML5 canvas.</canvas>

		<!-- Adding this for canvas to fill screen -->
		<style>
			* { margin: 0; padding: 0 }
			body, html { height: 100%; overflow: hidden; }
			#canvas {
				position: absolute;
				width: 100%; height: 100%;
				border: 1px solid black;
			}
		</style>
    </body>
	<script>
		var Box = function(x, y, direction)
		{
			this.x = x;
			this.y = y;
			this.direction = direction;
		}

		var canvas = document.getElementById("canvas");
		var ctx = canvas.getContext("2d");
		var snake = [];
		var head = new Box(100, 100, -1);
		canvas.width = window.innerWidth;
		canvas.height = window.innerHeight;
		ctx.fillStyle = "red";

		snake.push(head);
		//addBox();
		//addBox();
		//addBox();


		Box.prototype.draw = function()
		{
			ctx.fillRect(this.x, this.y, 20, 20);
		}

		function drawSnake()
		{
			//ctx.clearRect(0, 0, canvas.width, canvas.height);
			for (var i = 0; i < snake.length; i++)
			{
				switch (snake[i].direction)
				{
				case 0:
					snake[i].x -= 20;
					break;
				case 1:
					snake[i].y -= 20;
					break;
				case 2:
					snake[i].x += 20;
					break;
				case 3:
					snake[i].y += 20;
					break;
				}
			snake[i].draw();
			}
		}

		function addBox()
		{
			var lastBox = snake[snake.length - 1];
			var direction = lastBox.direction;
			var x, y;
			switch (direction)
			{
			case 0:
				x = lastBox.x + 20;
				y = lastBox.y;
				break;
			case 1:
				x = lastBox.x;
				y = lastBox.y + 20;
				break;
			case 2:
				x = lastBox.x - 20;
				y = lastBox.y;
				break;
			case 3:
				x = lastBox.x;
				y = lastBox.y - 20;
				break;
			}
			snake.push(new Box(x, y, direction));
		}

		document.addEventListener("keydown", function (event)
		{
			switch (event.keyCode)
			{
			case 37:
				head.direction = 0;
				break;
			case 38:
				head.direction = 1;
				break;
			case 39:
				head.direction = 2;
				break;
			case 40:
				head.direction = 3;
				break;
			}
		}, false);

		function gameLoop()
		{
			setTimeout("gameLoop()", 100);
			drawSnake();
		}

		gameLoop();
	</script>
</html>