JS中定义对象的几种方式

• 基于已有对象扩充其属性和方法

• 工厂方式

• 构造函数方式

• 原型(“prototype”)方式

• 动态原型方式

一,基于已有对象扩充其属性和方法

<script type="text/javascript">
var object = new Object();
object.name = "zhangsan";
object.sayName = function(name)
{
       this.name = name;
       alert(this.name);
}
object.sayName("lisi");
</script>

二,工厂方式

function createObject()
{
       var object = new Object();
       object.username = "zhangsan";
       object.password = "123";

       object.get = function()
       {
              alert(this.username + ", " + this.password);
       }
       return object;
}

var object1 = createObject();
var object2 = createObject();

object1.get();

• 改进：采用带参数的构造方法：

function createObject(username, password)
{
       var object = new Object();

       object.username = username;
       object.password = password;

       object.get = function()
       {
              alert(this.username + ", " + this.password);
       }

       return object;
}

var object1 = createObject("zhangsan", "123");

object1.get();

三,构造函数方式

function Person()
{
       //在执行第一行代码前，js引擎会为我们生成一个对象
       this.username = "zhangsan";
       this.password = "123";

       this.getInfo = function()
       {
              alert(this.username + ", " + this.password);
       } 

       //此处有一个隐藏的return语句，用于将之前生成的对象返回
       //只有在后面用new的情况下，才会出现注释所述的这两点情况

}

//生成对象
var person = new Person();//用了new
person.getInfo(); 

• 改进，带有参数

function Person(username, password)
{
       this.username = username;
       this.password = password;

       this.getInfo = function()
       {
              alert(this.username + ", " + this.password);
       }
}

var person = new Person("zhangsan", "123");
person.getInfo();