JavaScript面向对象之对象创建

1.创建对象：

var person = new Object();person.name = "zhangsan";person.age = 30;person.job = "software engineer";person.sayName = function(){alert(this.name);}person.sayName();

缺点：创造不同的对象需要大量重复的代码。

2.工厂模式：

function createObject(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 person1 = createObject("zhangsan",20,"teacher");var person2 = createObject("lisi",30,"doctor");person1.sayName();person2.sayName();

缺点：无法判断对象的类型。alert(typeof person1);alert(person1instanceof Object);

3.构造函数模式：

（1）

function Person(name,age,job){this.name = name;this.age = age;this.job = job;this.sayName = function (){alert(this.name);};}var person1 = new Person("zhangsan",20,"teacher");var person2 = new Person("lisi",30,"doctor");person1.sayName();person2.sayName();alert(person1.sayName == person2.sayName);

缺点：sayName方法执行同样的任务，但创建不同的对象时却要不同的Function。

（2）

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("zhangsan",20,"teacher");var person2 = new Person("lisi",30,"doctor");person1.sayName();person2.sayName();alert(person1.sayName == person2.sayName);

缺点：（2）虽然解决了（1）的问题，但sayName是一个全局函数，却只能被某个对象使用。如果对象由很多方法，就要定义很多全局函数，破坏了函数的封装性。

4.原型模式:

(1)

function Person(){}Person.prototype.name = "zhangsan";Person.prototype.age = 30;Person.prototype.job = "teacher";Person.prototype.sayName = function(){alert(this.name);};var person1 = new Person();person1.sayName();var person2 = new Person();person2.sayName();alert(person1.sayName == person2.sayName);

(2)

function Person(){}Person.prototype = {name:"zhangsan",age:30,job:"teacher",friends:["lisi","wangwu"],sayName:function(){alert(this.name);}};var person1 = new Person();var person2 = new Person();person1.friends.push("zhaoliu");alert(person1.friends);alert(person2.friends);alert(person1.friends == person2.friends);

缺点：由（2）可以看出原型的缺点，由于共享的特性，在使用基本类型时可以使用隐藏的手段解决，引用类型会造成共享问题。

5.组合构造函数模式和原型模式

function Person(name,age,job){this.name = name;this.age = age;this.job = job;this.friends = ["wangwu","zhaoliu"];}Person.prototype = {constructor:Person,sayName: function(){alert(this.name);}};var person1 = new Person("zhangsan",20,"teacher");var person2 = new Person("lisi",30,"doctor");person1.friends.push("liuqi");alert(person1.friends);alert(person2.friends);alert(person1.friends == person2.friends);alert(person1.sayName == person2.sayName);

6.动态原型模式

function Person(name,age,job){this.name = name;this.age = age;this.job = job;this.friends = ["wangwu","zhaoliu"];if(typeof this.sayName != "function"){Person.prototype.sayName = function (){alert(this.name);};}}var person1 = new Person("zhangsan",20,"teacher");var person2 = new Person("lisi",30,"doctor");person1.friends.push("liuqi");alert(person1.friends);alert(person2.friends);alert(person1.friends == person2.friends);alert(person1.sayName == person2.sayName);

7.寄生构造函数模式:

function Person(name,age,job){var o = new Object();o.name = name;o.age = age;o.job = job;o.friends = ["wangwu","zhaoliu"];o.sayName = function (){alert(this.name);};return o;}var person1 = new Person("zhangsan",20,"teacher");var person2 = new Person("lisi",30,"doctor");person1.friends.push("liuqi");alert(person1.friends);alert(person2.friends);alert(person1.friends == person2.friends);alert(person1.sayName == person2.sayName);

8.稳妥构造函数模式:

function Person(name,age,job){var o = new Object();o.sayName = function (){alert(name);};return o;}var person = Person("zhangsan",20,"teacher");person.sayName();

特点：与寄生构造函数模式相似，不同点在于一是不使用new调用构造函数，二是在创建对象的实例方法中不使用this.