<style>
.Food{background-color:red}
.Snake{background-color:blue}
</style>

<script>
var Rows=20
var Cells=30
var Num=15
var BorderWidth=5
var SpeedUp=5000

//創建地圖
function CreateMap(){
BW=eval(Cells*Num+2*BorderWidth)
BH=eval(Rows*Num+2*BorderWidth)
document.body.innerHTML='<div id=MainMap style=position:absolute;left:'+20+';top:'+20+';width:'+BW+';height:'+BH+';border-width:'+BorderWidth+';border-style:inset;border-color:#0000cc></div>'
Map=new Array()
for(y=0;y<Rows;y++){
	Map[y]=new Array()
	for(x=0;x<Cells;x++){
		Map[y][x]='0'
		}
	}
Sx=parseInt(Math.random()*Cells)
Sy=parseInt(Math.random()*Rows)
CreateSnake()
CreatFood()
AllDiv=MainMap.all.tags('DIV')
AllSpan=MainMap.all.tags('SPAN')
}




//創建食物的位置
function CreatFood(){
Fx=parseInt(Math.random()*Cells)
Fy=parseInt(Math.random()*Rows)
if(Map[Fy][Fx]=='0'){
	MainMap.innerHTML+='<span style=position:absolute;left:'+Fx*Num+';top:'+Fy*Num+';width:'+Num+';height:'+Num+';overflow:hidden class=Food></span>'
	Map[Fy][Fx]='F'
	}
else CreatFood()
}




//創建蛇的位置
function CreateSnake(){
MainMap.innerHTML+='<div x='+Sx+' y='+Sy+' style=position:absolute;left:'+Sx*Num+';top:'+Sy*Num+';width:'+Num+';height:'+Num+';overflow:hidden class=Snake></div>'
Map[Sy][Sx]='S'
}








//主移動--判斷蛇頭前面的是什么
function Move(){
Sx+=GoX
Sy+=GoY
if(Sy<0||Sy>=Rows)Move1()
else{
	SnakeFront=Map[Sy][Sx]
	if(SnakeFront=='0')Move2()
	else{
		if(SnakeFront=='F')Move3()
		else Move1()
		}
	}
}




//重新開始
function Move1(){
ReStart=confirm("Game Over，重新開始？")
if(ReStart)window.location.reload()
}

var Times=200

//蛇前是空地時

function Move2(){
Map[AllDiv[0].y][AllDiv[0].x]='0'
AllDiv[0].removeNode(true)
CreateSnake()
setTimeout('Move()',Times)
}

//蛇前面是食物時

function Move3(){
CreateSnake()
AllSpan[0].removeNode(true)
CreatFood()
setTimeout('Move()',Times)
}




//蛇越行越快
function oTimes(){
Times-=5
if(Times>5)setTimeout('oTimes()',SpeedUp)
}





document.onkeydown=KeyDown

//方向
function KeyDown(){
Key=event.keyCode
switch(Key){
case 37:Dir(-1,0);break//左
case 39:Dir(1,0);break//右
case 38:Dir(0,-1);break//上
case 40:Dir(0,1);break}//下
return false
}

var Star=0

function Dir(x,y){
GoX=x
GoY=y
if(Star==0){
	oTimes()
	Star=1
	Move()
	}
}




//開始時運行
onload=CreateMap
</script>