16.javascript中定义对象的几种方式（javascript中没有类的概念，只有对象）：
1）基于已有对象扩充其属性和方法：
var object = new Object();
object.name = "zhangsan";
object.sayName = function(name){
this.name = name;
alert(this.name);
}
object.sayName("lisi");
2）工厂方式：
//工厂方式创建对象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();//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();//让一个函数被多个对象共享，而不是每一个对象拥有一个函数对象function get(){ alert(this.username + ", " + this.password);}function createObject(username,password){ var object = new Object(); object.username = username; object.password = password; object.get = get; return object;}var object1 = createObject("zhangsan","123");var object2 = createObject("lisi","456");object1.get();object2.get();3）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 object.username = "zhangsan"; object.password = "123"; object.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}var person = new Person();person.getInfo();//可以在构造对象时传递参数function Person(username,password){ //在执行第一行代码前，js引擎会为我们生成一个对象 object.username = username; object.password = password; object.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}var person = new Person("zhangsan","123");person.getInfo();4）原型 （"prototype"）方式：
//使用原型 （prototype）方式创建对象function Person(){}Person.prototype.username = "zhangsan";Person.prototype.password= "123";Person.prototype.getInfo = function(){ alert(this.username + ", " + this.password);}var person1 = new Person();var person2 = new Person();person1.username = "lisi";person1.getInfo();person2.getInfo();//function Person(){}Person.prototype.username = new Array();Person.prototype.password= "123";Person.prototype.getInfo = function(){ alert(this.username + ", " + this.password);}var person1 = new Person();var person2 = new Person();person1.username.push("zhangsan");person1.username.push("lisi");person1.password= "456";person1.getInfo();person2.getInfo();//使用原型 + 构造函数方式来定义对象function Person(){ this.username = new Array(); this.password= "123";}Person.prototype.getInfo = function(){ alert(this.username + ", " + this.password);}var person1 = new Person();var person2 = new Person();person1.username.push("zhangsan");person2.username.push("lisi");person1.getInfo();person2.getInfo();5）动态原型方式：在构造函数中通过标志量让所有对象共享一个方法，而每个对象拥有自己的属性。
function Person(){ this.username = new Array(); this.password= "123"; if(typeof Person.flag == "undefined"){ alert("invoked"); Person.prototype.getInfo = function(){ alert(this.username + ", " + this.password); } Person.flag = true; }}var person1 = new Person();var person2 = new Person();person1.getInfo();person2.getInfo();
原标题：JS笔记2
关键词：JS
我知道了 