1.html结构如下（CSS忽略）
<h1>苏菲发的贪吃蛇</h1>
<div class="map"></div>
<input type="button" value="" id="btn" disabled="disabled" />
2.JS部分
// 根据id获取对象
function my$(Id){
return document.getElementById(Id);
}
<script>
// 根据id获取对象
function my$(Id){
return document.getElementById(Id);
}
my$("btn").onclick=function () {location.reload();
}
</script>
<script>
//食物
(function () {
var elements=[];
function Food(x,y,width,height,color) {
this.x=x||0;
this.y=y||0;
this.width=width||20;
this.height=height||20;
this.color=color||"green";
}
Food.prototype.init=function (map) {
remove();
var div=document.createElement("div");
map.appendChild(div);
div.style.width=this.width+"px";
div.style.height=this.height+"px";
div.style.backgroundColor=this.color;
div.style.position="absolute";
this.x=parseInt(Math.random()*(map.offsetWidth/this.width))*this.width;
this.y=parseInt(Math.random()*(map.offsetHeight/this.height))*this.height;
div.style.left=this.x+"px";
div.style.top=this.y+"px";
elements.push(div);
};
function remove() {
for(var i=0;i<elements.length;i++){
var ele=elements[i];
ele.parentNode.removeChild(ele);
elements.splice(i,1);
}
}
window.Food=Food;
}());
//蛇
(function () {
var elements=[];
function Snake(width,height,direction) {
this.width=width||20;
this.height=height||20;
//蛇身
this.body=[
{x:3,y:2,color:"red"},
{x:2,y:2,color:"orange"},
{x:1,y:2,color:"orange"}
];
this.direction=direction||"right";
}
Snake.prototype.init=function (map) {
remove();
for(var i=0;i<this.body.length;i++){
var obj=this.body[i];
var div=document.createElement("div");
map.appendChild(div);
div.style.position="absolute";
div.style.width=this.width+"px";
div.style.height=this.height+"px";
div.style.left=obj.x*this.width+"px";
div.style.top=obj.y*this.height+"px";
div.style.backgroundColor=obj.color;
elements.push(div);
}
};
Snake.prototype.move=function (food,map) {
//改变蛇身坐标
var i=this.body.length-1;
for(;i>0;i--){
this.body[i].x=this.body[i-1].x;
this.body[i].y=this.body[i-1].y;
}
//改变蛇头坐标
switch (this.direction){
case "right":this.body[0].x+=1;break;
case "left":this.body[0].x-=1;break;
case "top":this.body[0].y-=1;break;
case "bottom":this.body[0].y+=1;break;
}
//判断是否吃到食物，即判断蛇头与食物坐标是否一致
var headX=this.body[0].x*this.width;
var headY=this.body[0].y*this.height;
var foodx=food.x;
var foody=food.y;
if(headX==foodx&&headY==foody){
var last=this.body[this.body.length-1];
this.body.push({
x:last.x,
y:last.y,
color:last.color
});
food.init(map);
}
};
function remove() {
var i=elements.length-1;
for(;i>=0;i--){
var ele=elements[i];
ele.parentNode.removeChild(ele);
elements.splice(i,1);
}
}
window.Snake=Snake;
}());
//封装游戏
(function () {
var that=null;
var kaiShi=true;
function Game(map) {
this.food=new Food();
this.snake=new Snake();
this.map=map;
that=this;
}
//初始化游戏对象
Game.prototype.init=function (){
this.food.init(this.map);
this.snake.init(this.map);
// this.runSnake(this.food,this.map);//调用小蛇自动移动方法
this.bindKey();
my$("btn").value="按空格开始";
};
//让蛇移动
Game.prototype.runSnake=function (food,map) {
my$("btn").value="正在游戏";
var timeId=setInterval(function(){
this.snake.move(food,map);
this.snake.init(map);
var maxX=map.offsetWidth/this.snake.width;
var maxY=map.offsetHeight/this.snake.height;
var headX=this.snake.body[0].x;
var headY=this.snake.body[0].y;
if(headX<0||headX>=maxX){
clearInterval(timeId);
my$("btn").removeAttribute("disabled");
my$("btn").value="单击再玩一次";
}
if(headY<0||headY>=maxY){
clearInterval(timeId);
my$("btn").removeAttribute("disabled");
my$("btn").value="单击再玩一次";
}
}.bind(that),150);//bind的作用是讲实例化对象传给this，不传的话this就是window，会导致报错
};
//设置按键，改变蛇的方向
Game.prototype.bindKey=function () {
//获取用户按键，改变方向
document.addEventListener("keydown",function (e) {
switch(e.keyCode){
case 32 : if(kaiShi){this.runSnake(this.food,this.map);kaiShi=false;}break;//调用小蛇自动移动方法
case 37 : this.snake.direction=(this.snake.direction=="right"?"right":"left");break;
case 38 : this.snake.direction=(this.snake.direction=="bottom"?"bottom":"top");break;
case 39 : this.snake.direction=(this.snake.direction=="left"?"left":"right");break;
case 40 : this.snake.direction=(this.snake.direction=="top"?"top":"bottom");break;
}
}.bind(that),false);
};
window.Game=Game;
})();
//初始化游戏对象及游戏gm
var gm=new Game(document.querySelector(".map"));
gm.init();
</script>