HTML5 & JavaScript: Snake (Alpha Version)

Command:

$ cat html5game_snake.html


Result:

<canvas id="gc" width="640" height="480"></canvas>
<script>
rh=rv=0; //Resolution horizontal and vertical
sx=sy=1; //Snake position x and y
gx=gy=1; //Grid x and y
fps=60; //Frames per second
a=0.1; //Acceleration
v=1 //Velocity
vx=0; //Velocity x
vy=0; //Velocity y
dx=0; //Distance x
dy=0; //Distance y
gd=10; //Grid dimension
kc=39; //Key code
s=0; //Score

window.onload=function() {
c=document.getElementById('gc');
cc=c.getContext('2d');
setInterval(update,1000/fps); //reflesh screen fps times a second
window.addEventListener("keydown", function(e){
console.log(e.keyCode);
kc=e.keyCode;
});
rh=c.width/gd;
rv=c.height/gd;
}
function update(){
v+=a/fps; //Accelerate

if(kc==37){ //left
vx=-v;
vy=0;
} else if (kc==38) { //up
vx=0;
vy=-v;
} else if (kc==39) { //right
vx=v;
vy=0;
} else if (kc==40) { //down
vx=0;
vy=v;
}

dx=vx/fps;
dy=vy/fps;

s+=Math.abs(dx);
s+=Math.abs(dy);

sx+=dx;
sy+=dy;

//Snake boundary condition for x
while(sx<0 || sx>rh){
if(sx<0){
sx+=rh;
} else if(sx>rh){
sx-=rh;
}
}

//Snake boundary condition for y
while(sy<0 || sy>rv){
if(sy<0){
sy+=rv;
} else if(sy>rv){
sy-=rv;
}
}

gx=Math.round(sx);
gy=Math.round(sy);

if (gx < 1){
gx=rh;
} else if (gx>rh) {
gx=1;
}

if (gy < 1){
gy=rv;
} else if (gy>rv) {
gy=1;
}

//Finally Display
cc.fillStyle='black';
cc.fillRect(0,0,c.width,c.height);

//Food
cc.fillStyle='white';
cc.fillRect(gd*Math.round(rh/2),gd*Math.round(rv/2),gd,gd);

//Snake
cc.fillStyle='white';
cc.fillRect(gd*(gx-1),gd*(gy-1),gd,gd);
cc.fillText(v,100,100);
cc.fillText("score:" + Math.round(s),c.width-100,100);
}
</script>


Command:

$ open html5game_snake.html


Result:

HTML5 Snake Alpha