HTML5 Snake Game

Last some days I have been working with HTML5 canvas, sure it’s going to change the web future. I had implemented a snake game with HTML5 canvas + Javascript. Just take a look this live demo, it’s simple and light weight code you can use this script in 404 error pages and site down maintenance.

Live Demo

Developer

Arun Kumar Shekar
Engineer
Chennai, INDIA

Email : arunfairy[at]hotmail.com

facebook

twitter

Code
This code contains three functions play_game(), rand_frog() and set_game_speed(). If you want to change the game theme, modify these five variable values such as level, rect_w, rect_h, inc_score and snake_color.

<!documentTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>Play Snake Game</title>
<style type="text/css">
body {text-align:center;}
canvas { border:5px dotted #ccc; }
h1 { font-size:50px; text-align: center; margin: 0; padding-bottom: 25px;}
</style>
<script type="text/javascript">
function play_game()
{
var level = 160; // Game level, by decreasing will speed up
var rect_w = 45; // Width
var rect_h = 30; // Height
var inc_score = 50; // Score
var snake_color = "#006699"; // Snake Color
var ctx; // Canvas attributes
var tn = []; // temp directions storage
var x_dir = [-1, 0, 1, 0]; // position adjusments
var y_dir = [0, -1, 0, 1]; // position adjusments
var queue = [];
var frog = 1; // defalut food
var map = [];
var MR = Math.random;
var X = 5 + (MR() * (rect_w - 10))|0; // Calculate positions
var Y = 5 + (MR() * (rect_h - 10))|0; // Calculate positions
var direction = MR() * 3 | 0;
var interval = 0;
var score = 0;
var sum = 0, easy = 0;
var i, dir;
// getting play area
var c = document.getElementById('playArea');
ctx = c.getContext('2d');
// Map positions
for (i = 0; i < rect_w; i++)
{
map[i] = [];
}
// random placement of snake food
function rand_frog()
{
var x, y;
do
{
x = MR() * rect_w|0;
y = MR() * rect_h|0;
}
while (map[x][y]);
map[x][y] = 1;
ctx.fillStyle = snake_color;
ctx.strokeRect(x * 10+1, y * 10+1, 8, 8);
}
// Default somewhere placement
rand_frog();
function set_game_speed()
{
if (easy)
{
X = (X+rect_w)%rect_w;
Y = (Y+rect_h)%rect_h;
}
--inc_score;
if (tn.length)
{
dir = tn.pop();
if ((dir % 2) !== (direction % 2))
{
direction = dir;
}
}
if ((easy || (0 <= X && 0 <= Y && X < rect_w && Y < rect_h)) && 2 !== map[X][Y])
{
if (1 === map[X][Y])
{
score+= Math.max(5, inc_score);
inc_score = 50;
rand_frog();
frog++;
}
//ctx.fillStyle("#ffffff");
ctx.fillRect(X * 10, Y * 10, 9, 9);
map[X][Y] = 2;
queue.unshift([X, Y]);
X+= x_dir[direction];
Y+= y_dir[direction];
if (frog < queue.length)
{
dir = queue.pop()
map[dir[0]][dir[1]] = 0;
ctx.clearRect(dir[0] * 10, dir[1] * 10, 10, 10);
}
}
else if (!tn.length)
{
var msg_score = document.getElementById("msg");
msg_score.innerHTML = "Thank you for playing game.<br /> Your Score : <b>"+score+"</b><br /><br /><input type='button' value='Play Again' onclick='window.location.reload();' />";
document.getElementById("playArea").style.display = 'none';
window.clearInterval(interval);
}
}
interval = window.setInterval(set_game_speed, level);
document.onkeydown = function(e) {
var code = e.keyCode - 37;
if (0 <= code && code < 4 && code !== tn[0])
{
tn.unshift(code);
}
else if (-5 == code)
{
if (interval)
{
window.clearInterval(interval);
interval = 0;
}
else
{
interval = window.setInterval(set_game_speed, 60);
}
}
else
{
dir = sum + code;
if (dir == 44||dir==94||dir==126||dir==171) {
sum+= code
} else if (dir === 218) easy = 1;
}
}
}
</script>
</head>
<body onload="play_game()">
<h1>Play Snake Game</h1>
<div id="msg"></div>
<canvas id="playArea" width="450" height="300">Sorry your browser does not support HTML5</canvas>
</body>
</html>