提示：空格键控制开始/ 暂停，方向键控制蛇的移动方向，F5刷新

/*
 * @Author: CSU_XZY
 * @Date: 2020-10-17 12:38:26
 * @LastEditors: CSU_XZY
 * @LastEditTime: 2020-10-18 22:40:24
 * @FilePath: \第二天\snake\snake.js
 * @Description: just to play
 */
window.onload = function(){
 var snake = function(width,height,snakeId,speed){
  this.width = width || 10;
  this.height = height || 10;
  this.snakeId = snakeId || "snake";
  this.goX = 0;
  this.goY = 0;
  this.speed = this.oldSpeed = speed || 10;
  this.Grid = []; //存放td的二维数组
  this.snakeGrid = []; //存放蛇的数组
  this.foodGrid = [];
  this.snakeTimer = null;
  this.derectkey = 39;
  this.stop = true;
  this.init();
  document.getElementById("myAudio").play();
  box.style.animationPlayState = 'running'
 }

 snake.prototype = {
  //创建二维数组
  multiArray : function(m , n)
  {
   var array = new Array(m); //长
   for(let i = 0; i < m; i++)
   {
    array[i] = new Array(n); //宽
   }
   return array;
  },
  //函数修正this
  bind : function(fn,context)
  {
   return function(){
 return fn.apply(context,arguments);
 }
  },
  //移动的主函数
  move:function(){
 var _this = this;
 if(_this.snakeTimer){clearInterval(_this.snakeTimer);}
 _this.snakeTimer = setInterval(_this.bind(_this.main,_this),Math.floor(3000/this.speed));
  },
  //重来
  reset()
  {
   this.goX = 0;
   this.goY = 0;
   this.speed = this.oldSpeed;
   this.derectkey = 39;
   this.stop = true;
   this.init();
  },
  //确定键盘事件
  keyDown : function(e)
  { 
   var e = e || window.event;
   var keycode = e?e.keyCode:0;
   if(keycode == 116 )
   window.location.reload();
   if(keycode == 32)
   {
    if(this.stop)
    {
     this.move();
     this.stop = false;
    }
    else{
     if(this.snakeTimer)
     clearInterval(this.snakeTimer);
     this.stop = true;
    }
   }
   if(keycode>=37 && keycode <= 40)
    {
     if(!this.stop)
     this.derectkey = keycode;
    }
   return false;
  },
  //创建地图
  creatMap : function()
  {
   var table = document.createElement("table");
   var tbody = document.createElement("tbody");
   for(let i = 0; i < this.width; i++)
   {
    var tr = document.createElement("tr");
    for(let j = 0; j < this.height; j++)
    {
     var td = document.createElement("td");
     this.Grid[i][j] = tr.appendChild(td);
    }
    tbody.appendChild(tr);
   }
   table.appendChild(tbody);
   table.id = this.snakeId;
   document.body.appendChild(table);
  },
  //产生随机点
  randomPoint : function(initX,initY,endX,endY)
  {
   var p = []; //用来存放产生的随机点的数组
   var initX = initX || 0;
   var initY = initY || 0;
   var endX = endX || this.width;
   var endY = endY || this.height;
   p[0] = Math.floor(Math.random()*(endX - initX)) + Math.floor(initX);
   p[1] = Math.floor(Math.random()*(endY - initY)) + Math.floor(initY)
   return p;
  },
  //初始化食物的位置
  initFood : function()
  {
   this.foodGrid = this.randomPoint();

   if(this.isInSnake(this.foodGrid))
   {
    this.initFood();
    return false;
   }
   this.Grid[this.foodGrid[0]][this.foodGrid[1]].className = "food";
  },
  //判断点是否在蛇身上
  isInSnake : function(point,pos)
  {
   var snakeGrid = this.snakeGrid;
   if(point instanceof Array)
   {
    let n = snakeGrid.length;
    for(let i = pos || 0; i < n; i++)
    {
     if(point[0] == snakeGrid[i][0] && point[1] == snakeGrid[i][1])
     return true;
    }
   }
   return false;
  },
  //给蛇涂颜色
  paintSnake : function(){
   var snakeGrid = this.snakeGrid;
   for(let i = 0; i < snakeGrid.length; i++)
   {
    this.Grid[snakeGrid[i][0]][snakeGrid[i][1]].className = "snake_body";
   }
  },
  //初始化蛇的位置
  initSnake : function()
  {
   this.snakeGrid = [];

   this.snakeGrid.push([1,3]);
   this.snakeGrid.push([1,2]);
   this.snakeGrid.push([1,1]);

   this.paintSnake();

   this.Grid[this.snakeGrid[0][0]][this.snakeGrid[0][1]].className = "snake_head";
   this.Grid[this.snakeGrid[this.snakeGrid.length-1][0]][this.snakeGrid[this.snakeGrid.length-1][1]].className = "snake_tail";
  },
  //判断蛇是否撞墙
  isInWall : function(point){
   if(point instanceof Array){
    if(point[0] < 0 || point[0] > this.width1 - 1 || point[1] < 0 || point[1] > this.height - 1)
    return true;
   } 
   return false;
  },
  //初始化条件
  
  //控制函数运行的主函数
  main : function(){
   var snakeGrid = this.snakeGrid;
   var temp = snakeGrid[snakeGrid.length-1],
    isEnd = false;
    headX = snakeGrid[0][0];
    headY = snakeGrid[0][1];
    msg = "";
   switch(this.derectkey)
   {
    case 37:
  if(this.goY!=1){this.goY=-1;this.goX=0} //防止控制蛇往相反反方向走
  break;
 case 38:
  if(this.goX!=1){this.goX=-1;this.goY=0}
  break;
 case 39:
  if(this.goY!=-1){this.goY=1;this.goX=0}
  break;
 case 40:
  if(this.goX!=-1){this.goX=1;this.goY=0}
   }
   headX += this.goX;
   headY += this.goY;

   if(headX == this.foodGrid[0] && headY == this.foodGrid[1])
   {
    this.snakeGrid.unshift(this.foodGrid);
    this.initFood();
    if(this.snakeGrid.length>4){ //控制蛇加速
  if(this.snakeGrid.length==5){
  this.speed += 5;
  }
  else if(this.snakeGrid.length==10){
  this.speed += 3;
  }
  else if(this.snakeGrid.length==20){
  this.speed += 3;
  }
  else if(this.snakeGrid.length==30){
  this.speed += 3;
  }
  this.move();
 }
   }
   else
   {
    for(var i=this.snakeGrid.length-1;i>0;i--){
  this.snakeGrid[i] = this.snakeGrid[i-1] ;
 }
    this.snakeGrid[0] = [headX,headY]; 
    if(this.isInSnake(this.snakeGrid[0],1)){
  isEnd=true;
  msg = "哈皮，吃到自己啦！！";
 }
 //判断是否撞墙
 else if(this.isInWall(this.snakeGrid[0])){
  isEnd =true;
  msg = "撒比伟哥，撞墙了！！";
    }
    if(isEnd)
    {
     if(this.snakeTimer)
     clearInterval(this.snakeTimer);
     var score;
     let len = this.snakeGrid.length;
     if(len <= 5)
     score = len-3;
     else if(len>5 && len<=10)
     {
      score = 2 + 2*(len-5)
     }
     else if(len>10 && len <= 20)
     score = 12 + 3*(len-10);
     else
     score = 27 + 5*(len - 15);
     if(confirm(msg+"你的分数是："+score+"！ 是否重新开始？")){
  this.reset();
  }
  return false;
    }
    this.Grid[temp[0]][temp[1]].className = "notSnake";
   }
   this.paintSnake();
   this.Grid[headX][headY].className = "snake_head";
   this.Grid[this.snakeGrid[this.snakeGrid.length-1][0]][this.snakeGrid[this.snakeGrid.length-1][1]].className = "snake_tail";
  },
  init : function(){
   var _this = this;
   snake_id = document.getElementById(_this.snakeId)||0 ;
 if(snake_id){
 document.body.removeChild(snake_id);
 }
   _this.Grid = _this.multiArray(_this.width,_this.height);
   _this.creatMap();
   _this.initSnake();
   _this.initFood();
   document.onkeydown = _this.bind(_this.keyDown,_this);
  }
 }
 new snake(20,20,"snake",10);
}