js中怎么创建file对象

1、对已有对象进行扩充方法和属性

var object = new Object();

object.name = "zhangsan";//每个对象需要写这些语句
object.sayName = function(name){//每个对象需要写这些语句
    this.name = name;
};
object.sayName("lisi");
alert(object.name);

2、工厂方式创建对象

function createObject() {

    var object = new Object();
    object.username = "zhangsan";
    object.password = "123456";
    object.get = function(){
        alert(this.username + "," + this.password);
    }
    return object;
}
var object1 = createObject();
var object2 = createObject();
object1.get();
object2.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(){//缺点是，多少个对象则方法就有多少个
        alert(this.username + ", " + this.password);
    }
    return object;
}
var object1 = createObject("zhangsan",123456);
object1.get();

// 最佳改进方式
function get(){//使该函数被多个对象共享
    alert(this.username + ", " + this.password);
}
function createObject(username, password){//创建对象
    var object = new Object();
    object.username = username;
    object.password = password;
    object.get = get;
    return object;
}
var object1 = createObject("zhangsan", "123456");
var object2 = createObject("wangwu", "654321");
object1.get();
object2.get();

3、构造函数方式创建对象

function Person(){

    //在执行第一行代码欠，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，用于将之前生成对象返回。
}
var p1 = new Person();
p1.getInfo();

//带参数
function Person(username, password){
    this.username = username;
    this.password = password;
    this.getInfo = function(){
        alert(this.username + ", " + this.password);
    }
}
var p1 = new Person("zhangsan","1234546");
p1.getInfo();

4、原型（“prototype”）方式

function Person(){}

Person.prototype.username = "zhangsan";
Person.prototype.password = "123456";
Person.prototype.getInfo = function(){
    alert(this.username + ", " + this.password);
}

var person = new Person();
var person2 = new Person();
person.username = "haha";
person.getInfo();
person2.getInfo();

//单纯使用原型方式定义对象无法在构造函数中为属性赋值，只能在对象生成后再去改变属性值
function Person(){}

Person.prototype.username = new Array();
Person.prototype.password = "123456";

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

var person = new Person();
var person2 = new Person();
person.username.push("zhangsan");
person.username.push("lisi");
person.password = "321";
person.getInfo();
person2.getInfo();

5、综合方式（原型+构造函数方式搭配）

function Person(){

    this.username = new Array();//不被多个对象共享
    this.password = "123";
}

Person.prototype.getInfo = function()//被多个对象共享
{
    alert(this.username + "," + this.password);
}

var p1 = new Person();
var p2 = new Person();
p1.username.push("zhangsan");
p2.username.push("lisi");
p1.getInfo();
p2.getInfo();

6、动态原型方式

function Person(){
    this.username = "zhangsan";
    this.password = "123";
    //通过标志量让所有的对象共享方法
    if(typeof Person.flag == "undefined"){
        alert("prototype");
        Person.prototype.getInfo = function() {
            alert(this.username + ", " + this.password);
        }
        Person.flag = true;
    }
}

var p = new Person();
var p2 = new Person();
p.getInfo();
p2.getInfo();

ps：来源网络