javascript面向对象程序设计

来源：互联网发布：lol mac 编辑：程序博客网时间：2024/05/19 17:04

1、对象数据属性的类型
[Configurable]能否通过delete删除属性，能否修改属性特征，能够将数据属性改为访问器属性，默认值为true,一旦将变为false则不能修改其属性
[Enumberable]能否采用for-in循环返回属性，默认true
[Writable]是否可写
[Value]值默认undefined
eg：

2、访问器属性
[Configurable]
[Enumberable]
[Get]

[Set]

<!doctype><html><head><meta charset="UTF8"></head><script type="text/javascript">var person = {name:"guoxiaofen"};//writable属性Object.defineProperty(person,"name",{writable:false//将属性设置为不可修改})console.log(person.name);person.name = "amry";console.log("After write " + person.name);//configurableObject.defineProperty(person,"name",{//调用defineProperty属性若不指名属性名则默认均为falseconfigurable:false});console.log(person.name);delete person.name;console.log("After delete " + person.name);person.name = "小明";console.log("After write name " + person.name);// Object.defineProperty(person,"name",{//报错了// writable:true// });person.name = "小明";console.log("After write name " + person.name);//******************************************定义访问器属性*********************var book = {_year:2004,//标识只能通过访问器访问的属性edition:1}Object.defineProperty(book,"year",{set:function(newYear) {this._year = newYear;this.edition++;},get:function(){return this._year;}});book.year = 2005;console.log(book.edition);//或者通过如下方法定义访问器属性book.__defineGetter__('year1',function(){return this._year;});book.__defineSetter__('year1',function(newValue){this._year = newValue;this.edition++;});book.year1 = 2000;console.log(book.edition);//另一种定义数据和访问器属性的格式var myBook = {person:{value:"guoxiaofen"},_year:{value:2004},year:{get:function(){return this._year;},set:function(newValue){this._year = newValue;}}}//***************************************读取属性的特性var despriptor = Object.getOwnPropertyDescriptor(myBook,"year");console.log(despriptor.value.get);console.log(despriptor.configurable);//***************************************创建对象的方法//***************************************1.工厂模式,//*******缺点是下面的sayName函数就重复创建多次,而且不能很好地解决类别判断的问题 function createPerson(name,age,job){ var o = new Object(); o.name = name; o.age = age; o.job = job; o.sayName = function(){ alert(this.name); } return o; } var Bob = createPerson('Lilei',29,'worker'); var MeiMei = createPerson('HanMeimei',28,'computer'); console.log(Bob instanceof Object); //*********************************构造函数模式 //缺点是如果忘记new，则会把属性创建在全局作用域 function Person(name,age,job){ this.name = name; this.age = age; this.job = job; this.sayName = function(){ alert(this.name); } } var person1 = new Person('Lilei',20,"job"); var person2 = new Person('HanMeimei',20,'getOwnPropertyDescriptor'); console.log(person2.constructor == Person);//相当于对对象类别进行判断 console.log(person1 instanceof Person);//true console.log(person1.sayName == person2.sayName);//false //若将构造函数当成普通函数来使用，则在全局域创建属性 Person('world',30,'learning'); console.log(window.name); //对某一个函数使用 var p = new Object(); Person.call(p,'Lilei',40,'happy'); console.log(p.age); //**********************************************原型模式 //此类型对象可共享的内容最好放在原型链上 function Per(){} Per.prototype.name = "guoxiaofen"; Per.prototype.age = 23; Per.prototype.job = 'computer'; Per.prototype.sayName = function(){ alert(this.name); } var a = new Per(); var b = new Per(); console.log(a.name); a.name = "mada";//在自己的链上创建一个name属性，和prototype上的不是一个 console.log(b.name); console.log(a.name); console.log(a.__proto__); console.log(Per.prototype.isPrototypeOf(a)); //true, 虽然不能访问某个特定对象的[[prototype]],但是可以根据如上形式加以判断 //EMACscript新增访问prototype的方法,如下 console.log(Object.getPrototypeOf(a) == Per.prototype);//true console.log(Object.getPrototypeOf(a)); //hasOwnProperty()函数,判断自己是否有某个属性 a.name = "天才"; console.log(a.hasOwnProperty("name")); console.log(b.hasOwnProperty("name")); //原型模式与in操作符 console.log(a.name);//天才 console.log("name" in a); //true 自己的属性 delete a.name; console.log("name" in a);//true  原型链上的属性 console.log(a.name);//guoxiaofen //for-in()  所有可枚举属性，包括原型链上的 for(c in a){ console.log("a 的 " + c); }</script></html>

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