javascript没有类这个概念，但是面向对象的标志确是拥有类概念。对于类抽象重复的解决方案在javascript中没有办法通过继承来实现。但是javascript的每个函数都自动添加一个名称为prototype属性，这是一个对象，我们可以将所有的实例通过一个原型链引用到prototype上，从而模拟类的方式。
原型模式实现一个接口，该接口用于创建当前对象的克隆，从而实现创建重复的对象。
在javascript中的继承关系就可以通过原型克隆一份父类给子类便可。我们可以定义一个所有类型的父类Class来实现继承的函数，所有其他类通过继承父类。Class类的代码如下：
function Class(){}
Class.extend = function(prop){
var _super = this.prototype;
initializing = true;
var prototype = new this();
initializing = false;
fnTest = /xyz/.test(function(){xyz;})?/\b_super\b/:/.*/;
for(var name in prop){
prototype[name] = typeof prop[name] == "function"&&typeof _super[name] == "function"&&fnTest.test(prop[name])?
(function(name,fn){
return function(){
var tmp = this._super;
this._super = _super[name];
var ret = fn.apply(this,arguments);
this._super = tmp;
return ret;
};
})(name,prop[name]):
prop[name];
}
function Class(){
if(!initializing){
if(!this.ctor)
return;
else
this.ctor.apply(this,arguments);
}
}
Class.prototype = prototype;
Class.prototype.constructor = Class;
Class.extend = arguments.callee;
return Class;
};
第23行代码重写了Class(),定义了ctor作为构造函数，第8行到第19行根据prop的变量类型将父类的属性和方法克隆给子类，实现继承和重载的功能，同时定义_super来实现调用父类方法的功能。
下面是一个Class函数的应用，通过模拟游戏打怪的方式，类图：
效果图：
实现代码：
<script>
var mouse = null,shark = null;
var player = new Player(20,500);
function metMouse(){
mouse = new Mouse(10,10,5,100);
console.log("在("+mouse.x + "," + mouse.y +")生成老鼠");
document.getElementById("mouseid").style.display = "block";
setInterval(function(){
if(!mouse.isDie())
player.hurt(mouse.att);
else
console.log("老鼠已经死了");
},2000);
}
function metShark(){
shark = new Shark(10,15,10,120);
console.log("在("+shark.x + "," + shark.y +")生成鲨鱼");
document.getElementById("sharkid").style.display = "block";
setInterval(function(){
if(!shark.isDie())
player.hurt(shark.att);
else
console.log("鲨鱼已经死了");
},2000);
}
function attackMouse(){
mouse.hurt(player);
}
function attackShark(){
shark.hurt(player);
}
</script>
</head>
<body>
<button onclick = "metMouse()">遇见老鼠</button>
<button onclick = "metShark()">遇见鲨鱼</button>
<button onclick = "attackMouse()" style = "display:none;" id = "mouseid">攻击老鼠</button>
<button onclick = "attackShark()" style = "display:none;" id = "sharkid">攻击鲨鱼</button>
</body>
怪兽的代码：
var Monster = Class.extend({
ctor:function(_x,_y,_att,_blood){
this.x = _x,
this.y = _y,
this.att = _att;
this.blood = _blood;
},
attack:function(player){
player.hurt(this.att);
},
hurt:function(player){
this.blood -= player.att;
console.log("怪兽受到" + player.att + "攻击");
console.log("怪兽当前血量：" + this.blood);
},
isDie:function(){
return this.blood <= 0;
}
});
玩家的代码：
var Player = Class.extend({
ctor:function(_att,_blood){
this.att = _att;
this.blood = _blood;
},
hurt:function(_att){
this.blood -= _att;
console.log("玩家受到" + _att + "伤害");
console.log("玩家当前血量为：" + this.blood);
}
});
Shark类
var Shark = Monster.extend({
attack:function(player){
_super.attack(player);
player.hurt(20);
console.log("鲨鱼怪物给玩家造成额外的20点伤害");
},
hurt:function(player){
console.log("鲨鱼怪皮厚，减少10点伤害");
this.blood = this.blood - player.att + 10;
console.log("鲨鱼受到" + (player.att - 10) + "点伤害");
console.log("鲨鱼当前血量：" + this.blood);
}
});
时间： 2024-10-20 20:30:05