看了书，发现自己写的贪吃蛇代码并不对……于是把JavaScript代码给改了下：

(function () {/*全局变量*/var g = {//获得or设置盒子的attributeattr : function (x, y, att, name) {var d = document.getElementById("box_" + x + "_" + y);if (d && name)d.setAttribute(att, name);else if (d)return d.getAttribute(att);},//随机创建点create : function (start, end) {return Math.floor(Math.random() * (end - start) + start);},//运动方向direction : {left : 37,up : 38,right : 39,down : 40},//游戏设定setting : {size : 20,speed : 500,len : 3,func : null,direct : null}}/*Game构造器*/function Game () {};/*创建格子*/Game.prototype.pannel = function () {var t = [];t.push("<table>");for (var i = 0; i < g.setting.size; i ++) {t.push("<tr class = 'row' y = " + i + ">");for (var j = 0; j < g.setting.size; j ++) {t.push("<td id = 'box_" + j + "_" + i + "'></td>");}t.push("</tr>");}t.push("</table>");document.getElementById("pannel").innerHTML = t.join("");};/*初始化游戏*/Game.prototype.init = function () {if (g.setting.func)window.clearInterval(g.setting.func);var d = document.getElementById("start"); if (d)d.disabled = false;for (var x = 0; x < g.setting.size; x ++)for (var y = 0; y < g.setting.size; y ++)g.attr(x, y, "class", " ");}/*游戏开始*/Game.prototype.start = function () {g.setting.direct = g.direction.down;var snake = new Snake(), food = new Food();food.create();snake.create();//蛇移动g.setting.func = window.setInterval(function() {snake.move();}, g.setting.speed);}/*监听键盘*/Game.prototype.listen = function (e) {e = e || event;g.setting.direct = Math.abs(e.keyCode - g.setting.direct) != 2 && e.keyCode > 36 && e.keyCode < 41 ? e.keyCode : g.setting.direct;}/*游戏结束*/Game.prototype.over = function () {alert("game over XD!");game.init();};/*Snake构造器*/function Snake () {this.headX = 0;this.headY = 0;this.lastX = 0;this.lastY = 0;this.pos = [];};/*创建蛇*/Snake.prototype.create = function () {var x = g.create(g.setting.len, g.setting.size / 2),y = g.create(g.setting.len, g.setting.size / 2);//获得蛇的坐标for (var i = 0; i < g.setting.len; i ++) {y --;this.pos.push([x, y]);g.attr(x, y, "class", "snake");}};/*移动*/Snake.prototype.move = function () {this.headX = this.pos[0][0];this.headY = this.pos[0][1];this.lastX = this.pos[this.pos.length - 1][0];this.lastY = this.pos[this.pos.length - 1][1];g.attr(this.lastX, this.lastY, "class", " ");for (var i = this.pos.length - 1; i > 0; i --) {this.pos[i][0] = this.pos[i - 1][0];this.pos[i][1] = this.pos[i - 1][1];}switch (g.setting.direct) {case g.direction.up : this.headY    -= 1; break;case g.direction.down : this.headY  += 1; break;case g.direction.left : this.headX  -= 1; break;case g.direction.right : this.headX += 1; break;}this.pos[0][0] = this.headX;this.pos[0][1] = this.headY;for (var i = 0; i < this.pos.length; i ++)g.attr(this.pos[i][0], this.pos[i][1], "class", "snake");var inside = g.attr(this.headX, this.headY, "inside");if (inside == "food") {this.lastX = this.pos[this.pos.length - 1][0];this.lastY = this.pos[this.pos.length - 1][1];if (this.lastX == this.pos[this.pos.length - 2][0]) {if (this.lastY - this.pos[this.pos.length - 2][1] == 1)this.pos.push([this.lastX, this.lastY + 1]);else if (this.pos[this.pos.length - 2][1] - this.lastY == 1)this.pos.push([this.lastX, this.lastY - 1]);}else if (this.lastY == this.pos[this.pos.length - 2][1]) {if (this.lastX - this.pos[this.pos.length - 2][0] == 1)this.pos.push([this.lastX + 1, this.lastY])else if (this.pos[this.pos.length - 2][0] - this.lastX == 1)this.pos.push([this.lastX - 1, this.lastY]);}this.lastX = this.pos[this.pos.length - 1][0];this.lastY = this.pos[this.pos.length - 1][1];g.attr(this.lastX, this.lastY, "class", "snake");var food = new Food(); //其实这一步可以改food.create();};//撞到自己或者墙，游戏结束for (var i = 1; i < this.pos.length; i ++) {if (this.headX == this.pos[i][0] && this.headY == this.pos[i][1])game.over();elsecontinue;}if (this.headX > 19 || this.headX < 0 || this.headY > 19 || this.headY < 0)game.over();};/*Food构造器*/function Food () {};/*创建食物*/Food.prototype.create = function () {var that = this;var x = g.create(0, g.setting.size),y = g.create(0, g.setting.size);//检查是否与蛇的位置重合var c = g.attr(x, y, "class");if (c == "snake")return that.create();else {g.attr(x, y, "class", "food");g.attr(x, y, "inside", "food");}};var game = new Game();game.pannel();game.init();document.getElementById("start").onclick = function() {this.disabled = true;game.start();window.onkeydown = game.listen;}})()

恩，大概就是这样。和我上一次的代码区别在以下几个方面：

• 确实实现了代码复用；
• 这次的对象是正确声明的了；

对了我想总结一下改的时候的一个问题：原来的Snake对象中，我是将Snake的pos、headX、headY、lastX、lastY都设置为私有变量的，结果这一次修改的时候我把它们改成了实例属性。但是因为用了setTimeout来调用snake.move，所以一开始的snake.move函数里面的this是指向全局的，就会导致无法运行，于是我干脆写了个匿名函数把snake.move给闭包了……算是一个不值一提的小技巧吧(⊙﹏⊙)b，总结一下免得自己忘了o(╯□╰)o