还记得诺基亚手机上贪吃蛇小游戏吗？

//构造方块对象
    function Rect(x,y,w,h,color){
        this.x = x;
        this.y = y;
        this.w = w;
        this.h = h;
        this.color = color;
    }

    //画方块的方法
    Rect.prototype.draw = function(){
        context.beginPath();
        context.fillStyle= this.color;
        context.rect(this.x,this.y,this.w,this.h);
        context.fill();
        context.stroke();
    }

    //构造蛇对象
    function Snake(){

        //定义一个数组存放一整条蛇的方块对象
        var snakeArray = [];
        var start_num = 4;  //方块开始数量
        this.snake_head_color = snake_head_color;   //蛇头颜色
        this.rect_color = rect_color;    //方块颜色

        //生成4个灰色方块
        for(var i=0;i<start_num;i++){
            var rect = new Rect(i*20,0,20,20,this.rect_color);
            snakeArray.splice(0,0,rect);
        }

        var head = snakeArray[0];
        head.color = this.snake_head_color;

        this.head = snakeArray[0];
        this.snakeArray = snakeArray;

        //给定初始位置向右(keyCode右箭头)
        this.direction = 39;
    }

    //画蛇的方法
    Snake.prototype.draw = function (){
        for(var i=0;i<this.snakeArray.length;i++){
            this.snakeArray[i].draw();
        }
    }

    //蛇移动的方法(重点)
    Snake.prototype.move = function(){
        //1、画一个方块位置与蛇头重叠
        //2、将这个方块插入蛇头后面一个的位置
        //3、然后将最后一个方块删除即可
        //4、将蛇头向指定的方向移动一格

        var rect = new Rect(this.head.x,this.head.y,this.head.w,this.head.h,this.rect_color);
        this.snakeArray.splice(1,0,rect);

        //判断是否吃到食物
        if(isEat()){
            score +=score_increment;
            total_score.innerText = score;
            food = new getRandomFood();
        }else{
            this.snakeArray.pop();
        }

        //设置蛇头的运动方向，37、A(65)左，38、W(87)上，39、D(68)右，40、S(83)下
        if(this.direction==37||this.direction==65){ //左
            this.head.x -= this.head.w;
        }else if(this.direction==38||this.direction==87){//上
            this.head.y -= this.head.h;
        }else if(this.direction==39||this.direction==68){//右
            this.head.x += this.head.w;
        }else if(this.direction==40||this.direction==83){//下
            this.head.y += this.head.h;
        }

        //GameOver判定
        //撞墙
        if(this.head.x+1 >mCanvas.width || this.head.x<0 || this.head.y+1>mCanvas.height || this.head.y<0){

            //判定是否无墙模式
            if(hasWall){
                if(this.head.x > mCanvas.width){
                    this.head.x = 0;
                }

                if(this.head.x < 0){
                    this.head.x = mCanvas.width;
                }

                if(this.head.y > mCanvas.height){
                    this.head.y = 0;
                }

                if(this.head.y < 0 ){
                    this.head.y = mCanvas.height;
                }
            }else{
                closeInterval();    //关闭定时器
                setTimeout(function(){
                    //location.reload();
                    game_over();    //游戏结束
                },1500);
            }


        }

        //撞自己
        for(var i=1;i<this.snakeArray.length;i++){
            if(this.snakeArray[i].x == this.head.x && this.snakeArray[i].y == this.head.y){
                closeInterval();
                setTimeout(function(){
                    //location.reload();
                    game_over();
                },1500);
            }
        }
    }

    //画出初始的蛇
    var snake = new Snake();
    snake.draw();
    snake_length.innerText = snake.snakeArray.length;

    //画出初始的食物
    var food = new getRandomFood();

    var timer = null;
     //开启定时器
    function startInterval(){
            if(timer==null){
                timer = setInterval(function (){
                    context.clearRect(0,0,mCanvas.width,mCanvas.height);
                    food.draw();
                    snake.move();
                    snake.draw();
                    snake_length.innerText = snake.snakeArray.length;
                },movement);
            }
    }