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();
转载于:https://www.cnblogs.com/zhengsha/p/5086455.html
