JavaScript学习进程（2）

创建对象

1.工厂模式

例子：

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  person1 = createPerson("Nichilos","29","Soft Engineer");
var  person2 = createPerson("Grey","27","Doctor");

2.构造函数模式

 构造函数与其他函数唯一的区别就是调用它们的方式不同

例子

function Person(name , age , job){
     this.name = name;
     this.age = age;
     this.job = job;
     this.sayName = function(){
         alert(this.name);
      };
 }
   //当做构造函数调用
   var person1 = new Person("Nicholos","29","Software Engineer");
   person1.sayName();//"Nicholos"
   //作为普通函数调用
   Person("Grey","29","Software Engineer");//添加到window
   window.sayName();//"Grey"
   //在另一个对象的作用域中调用
   var o = new Object();
   Person.call(o,"Kreis","24","Nurse");
   o.sayName();//"Kreis"

　特点1：没有显示的创建对象；

特点2：直接将属性和方法赋给了this对象；

特点3：没有return语句。

存在的问题：

   alert(person1.sayName==person2.sayName); //false

　　将函数定义转移到构造函数之外

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("Nichilos","29","Soft Engineer");
   var  person2 = new Person("Grey","27","Doctor");

3.原型模式

function Person(){
}
Person.prototype.name = "Nicholos";
Person.prototype.age = "29";
Person.prototype.job = "Software Engineer";
Person.prototype.sayName = function(){
            alert(this.name);
};
var person1 = new Person();
person1.name = "Grey";
alert(person1.name);//"Grey"
person1.sayName();// "Nicholos"
var person2 = new Person();
alert(person2.name);//"Nicholos""
alert(person1.sayName == person2.sayName);//ture

4.组合使用构造函数和原型函数模式

function Person(name , age ,job){
this.name = name;
this.age = age;
this.job = job;
this.friends = ["Shelby","Court"];}
Person.prototype = {
constructor : Person,
sayName : function(){
alert(this.name);
}
}
var  person1 = new Person("Nichilos","29","Soft Engineer");
var  person2 = new Person("Grey","27","Doctor");
person1.friends.push("Van");
alert(person1.friends);//"Shelby","Court","Van"
alert(person2.friends);//"Shelby","Court"
alert(person1.friends == person2.friends);//false
alert(person1.sayName == person2.sayName);//true