javascript面向对象编程
在javascript中最简单的创建一个对象的方式如下：var person = new Object();person.name = "海绵宝宝";person.age = 27;person.job = "software engineer";person.sayName = function(){ alert(this.name);}person.sayName();
工厂模式，如下所示：
function createPerson (name,age,job){ var o = new Object(); o.name = name; o.age = age; o.job = job; o.sayName = function(){ alert(this.name); } return o;}var person = createPerson("Frederick",27,"software engineer");person.sayName();
构造函数模式，如下所示：
function Person(name,age,job){ this.name = name; this.age = age; this.job = job; this.sayName = function(){ alert(this.name); }}var person1 = new Person("海绵宝宝",27,"software engineer");var person2 = new Person("Frederick","29","Manager");person1.sayName();//海绵宝宝person2.sayName();//Frederick 上面的构造函数模式有个缺点，每个方法都要在创建每个实例时重新创建一遍，如上person1和person2都有一个名为sayName()的方法，但是两个方法不是同一个Function实例。简单的改进方法如下：
function Person(name,age,job){ this.name = name; this.age = age; this.job = job; this.sayName = sayName;}function sayName(){ alert(this.name);}var person1 = new Person("海绵宝宝",27,"software engineer");var person2 = new Person("Frederick",29,"Manager");person1.sayName();//海绵宝宝person2.sayName();//Frederick 上面改造之后我们把sayName放到了构造函数之外，在构造函数内部person1和person2通过指针引用指向了全局的sayName()方法，这样一来person1和person2就共享了全局的sayName()方法。这样做同样有缺点——多出了一个名不副实的全局函数，如果对象的方法很多就会有很多这样的全局函数，为了解决这些问题可以采用下面的原型模式。
原型模式，如下所示：
function Person(){}Person.prototype.name = "海绵宝宝";Person.prototype.age = 27;Person.prototype.job = "software engineer";Person.prototype.sayName = function(){ alert(this.name);}var person1 = new Person();person1.sayName();var person2 = new Person();person2.sayName(); 上面的方式显然还不够好，所有的实例都共享相同的信息，为此我们可以再改造一下。
组合使用构造函数模式和原型模式，如下所示：
function Person(name,age,job){ this.name = name; this.age = age; this.job = job; this.friends = ['Tom','Jerry'];}Person.prototype = { constructor: Person, sayName: function(){ alert(this.name); }}var person1 = new Person("海绵宝宝",27,"software engineer");var person2 = new Person("Frederick",29,"Manager");person1.friends.push("Nancy");alert(person1.friends);//Tom,Jerry,Nancyalert(person2.friends);//Tom,Jerryalert(person1.sayName == person2.sayName);//true
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