Javascript对象定义的几种方式

Javascript对象定义的几种方式一.工厂方式：先创建对象，再向对象添加方法和属性，封闭后调用不要使用new操作符创建对象。使用这种方法有很多弊端，把方法定义在工厂函数内部的时候，每次调用的时候都会产生新的函数function factory(name,person,address,time){    var tmp=new Object;    tmp.name=name;    tmp.person=person;    tmp.address=address;    tmp.workTime=function(){        alert("we start to work at" + time);    }    return tmp;}var factory1=factory("drugs",100,"huashan Rd",10);var factory2=factory("TCMdrugs",100,"hongqiao Rd",11);factory1.workTime();factory2.workTime();//Here,factory1 and factory2 have different method对这种问题虽然可以用下面的方式改进，但是缺乏很好的封装性function factory(name,person,address,time){    var tmp=new Object;    tmp.name=name;    tmp.person=person;    tmp.address=address;    tmp.workTime=workTime();    return tmp;}function workTime(){    alert("we start to work at" + this.time);}二，构造函数方式，在构造函数内部不创建对象，使用this关键字，使用时候用new操作符，存在和工厂方式相同的问题，重复创建函数。function counstruct(name,person,address,time){    this.name=name;    this.person=person;    this.address=address;    this.workTime=function(){        alert("we start to work at" + this.time);    };}三.原型方式：利用prototype属性来实现属性和方法，可以通过instanceof 检查对象类型，解决了重复创建函数的问题，但不能通过传递参数初始化属性function Car(){ }Car.prototype.color = "red";Car.prototype.doors = 4;Car.prototype.mpg = 23;Car.prototype.showColor = function(){    alert(this.color);};var car1 = new Car();var car2 = new Car();但是如果遇到下面的情况，又出问题了Car.prototype.drivers = new Array("mike", "sue");car1.drivers.push("matt");alert(car1.drivers);  //outputs "mike,sue,matt"alert(car2.drivers);  //outputs "mike,sue,matt"drivers是指向Array对象的指针，Car的两个实例都指向同一个数组。四.混合的构造函数/原型方式:针对原型方式的解决方案function Car(sColor, iDoors, iMpg){    this.color = sColor;    this.doors = iDoors;    this.mpg = iMpg;    this.drivers = new Array("mike", "sue");}Car.prototype.showColor = function (){    alert(this.color);};var car1 = new Car("red", 4, 23);var car2 = new Car("blue", 3, 25);car1.drivers.push("matt");alert(car1.drivers);alert(car2.drivers);五.动态原型方式:这种方式是极力推荐的方式，避免了前面几种方式所出现的问题，提供了更友好的编码风格function Car(sColor, iDoors, iMpg){    this.color = sColor;    this.doors = iDoors;    this.mpg = iMpg;    this.drivers = new Array("mike", "sue");        if(typeof Car.initialized == "undefined"){        Car.prototype.showColor = function (){            alert(this.color);        };        Car.initialized = true;    }} var car1 = new Car("red", 4, 23);var car2 = new Car("blue", 3, 25); car1.drivers.push("matt");alert(car1.drivers);alert(car2.drivers);六.混合工厂方式：和工厂方式有些相似，但采用new关键字实例化，具有和工厂方式相同的弊端，不推荐使用