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.