面向对象的三大基本特性

封装(把相关的信息（无论数据或方法）存储在对象中的能力)

继承(由另一个类（或多个类）得来类的属性和方法的能力)

多态(一个对象在不同情况下的多种形态)

定义类或对象

第一种：基于Object对象

var person = new Object();person.name = "Rose";person.age = 18;person.getName = function () { return this.name;};console.log(person.name);//Roseconsole.log(person.getName);//function () {return this.name;}console.log(person.getName());//Rose

缺点：不能创建多个对象。

第二种：基于字面量方式

var person = { name : "Rose", age : 18 , getName : function () { return this.name; }};console.log(person.name);//Roseconsole.log(person.getName);//function () {return this.name;}console.log(person.getName());//Rose

优点：比较清楚的查找对象包含的属性和方法；

缺点：不能创建多个对象。

第三种：工厂模式

方式一：

function createPerson(name,age) { var object = new Object(); object.name = name; object.age = age; object.getName = function () { return this.name; }; return object;}var person1 = createPerson("Rose",18);var person2 = createPerson("Jack",20);console.log(person1.name);//Roseconsole.log(person2.name);//Jackconsole.log(person1.getName === person2.getName);//false//重复生成函数，为每个对象都创建独立的函数版本

优点：可以创建多个对象；

缺点：重复生成函数getName()，为每个对象都创建独立的函数版本。

方式二：

function createPerson(name,age) { var object = new Object(); object.name = name; object.age = age; object.getName = getName; return object;}function getName() { return this.name;}var person1 = createPerson("Rose",18);var person2 = createPerson("Jack",20);console.log(person1.name);//Roseconsole.log(person2.name);//Jackconsole.log(person1.getName === person2.getName);//true//共享同一个函数

优点：可以创建多个对象；

缺点：从语义上讲，函数getName()不太像是Person对象的方法，辨识度不高。

第四种：构造函数方式

方式一：

function Person(name,age) { this.name = name; this.age = age; this.getName = function () { return this.name; }}var person1 = new Person("Rose",18);var person2 = new Person("Jack",20);console.log(person1.name);//Roseconsole.log(person2.name);//Jackconsole.log(person1.getName === person2.getName); //false//重复生成函数，为每个对象都创建独立的函数版本

优点：可以创建多个对象；

缺点：重复生成函数getName()，为每个对象都创建独立的函数版本。

方式二：

function Person(name,age) { this.name = name; this.age = age; this.getName = getName ;}function getName() { return this.name;}var person1 = new Person("Rose",18);var person2 = new Person("Jack",20);console.log(person1.name);//Roseconsole.log(person2.name);//Jackconsole.log(person1.getName === person2.getName); //true//共享同一个函数

优点：可以创建多个对象；

缺点：从语义上讲，函数getName()不太像是Person对象的方法，辨识度不高。

第五种：原型方式

function Person() {}Person.prototype.name = 'Rose';Person.prototype.age = 18;Person.prototype.getName = function () { return this.name;};var person1 = new Person();var person2 = new Person();console.log(person1.name);//Roseconsole.log(person2.name);//Rose//共享同一个属性console.log(person1.getName === person2.getName);//true//共享同一个函数

缺点：它省略了为构造函数传递初始化参数，这在一定程序带来不便；另外，最主要是当对象的属性是引用类型时，它的值是不变的，总是引用同一个外部对象，所有实例对该对象的操作都会影响其它实例：

function Person() {}Person.prototype.name = 'Rose';Person.prototype.age = 18;Person.prototype.lessons = ["语文","数学"];Person.prototype.getName = function () { return this.name;};var person1 = new Person();person1.lessons.push("英语");var person2 = new Person();console.log(person1.lessons);//["语文", "数学", "英语"]console.log(person2.lessons);//["语文", "数学", "英语"]//person1修改影响了person2

第六种：构造函数+原型方式（推荐）

function Person(name,age) { this.name = name; this.age = age;}Person.prototype.getName = function () { return this.name;};var person1 = new Person('Rose', 18);var person2 = new Person('Jack', 20);console.log(person1.name);//Roseconsole.log(person2.name);//Jackconsole.log(person1.getName === person2.getName);//true//共享原型中定义的方法

缺点：属性定义在构造函数内，方法定义在构造函数外，与面向对象的封装思想不符。

第七种：构造函数+动态原型方式（推荐）

方式一：

function Person(name,age) { this.name = name; this.age = age; if (typeof Person._getName === "undefined"){ Person.prototype.getName = function () { return this.name; }; Person._getName = true; }}var person1 = new Person('Rose', 18);var person2 = new Person('Jack', 20);console.log(person1.name);//Roseconsole.log(person2.name);//Jackconsole.log(person1.getName === person2.getName);//true//共享原型中定义的方法

方式二：

function Person(name,age) { this.name = name; this.age = age; if (typeof this.getName !== "function"){ Person.prototype.getName = function () { return this.name; }; }}var person1 = new Person('Rose', 18);var person2 = new Person('Jack', 20);console.log(person1.name);//Roseconsole.log(person2.name);//Jackconsole.log(person1.getName === person2.getName);//true//共享原型中定义的方法

对象属性的扩展及删除

Javascript的对象可以使用 '.' 操作符动态的扩展其属性，可以使用 'delete' 关键字或将属性的值设置为 'undefined' 来删除属性。

function Person(name,age) { this.name = name; this.age = age; if (typeof Person._getName === "undefined"){ Person.prototype.getName = function () { return this.name; }; Person._getName = true; }}var person = new Person("Rose",18);person.job = 'Engineer';//添加属性console.log(person.job);//Engineerdelete person.job;//删除属性console.log(person.job);//undefined//删除属性后值为undefinedperson.age = undefined;//删除属性console.log(person.age);//undefined//删除属性后值为undefined

对象属性类型

数据属性

特性：

[configurable]:表示能否使用delete操作符删除从而重新定义，或能否修改为访问器属性。默认为true;

[enumberable]:表示是否可通过for-in循环返回属性。默认true;

[writable]:表示是否可修改属性的值。默认true;

[value]:包含该属性的数据值。读取/写入都是该值。默认为undefined;如上面实例对象person中定义了name属性，其值为'My name',对该值的修改都反正在这个位置

function Person(name,age) { this.name = name; this.age = age; if (typeof Person._getName === "undefined"){ Person.prototype.getName = function () { return this.name; }; Person._getName = true; }}var person = new Person("Rose",18);Object.defineProperty(person,"name",{configurable:false,writable:false});person.name = "Jack";console.log(person.name);//Rose//重新赋值无效delete person.name;console.log(person.name);//Rose//删除无效

注意：

一旦将configurable设置为false，则无法再使用defineProperty将其修改为true（执行会报错：cannot redefine property : propertyName）

function Person(name,age) { this.name = name; this.age = age; if (typeof Person._getName === "undefined"){ Person.prototype.getName = function () { return this.name; }; Person._getName = true; }}var person = new Person("Rose",18);Object.defineProperty(person,"name",{configurable:false,writable:false});person.name = "Jack";console.log(person.name);//Rose//重新赋值无效delete person.name;console.log(person.name);//Rose//删除无效Object.defineProperty(person,"name",{configurable:true,writable:true});//Cannot redefine property: name

访问器属性

特性：

[configurable]:是否可通过delete操作符删除重新定义属性；

[numberable]:是否可通过for-in循环查找该属性；

[get]:读取属性时调用，默认：undefined;

[set]:写入属性时调用，默认：undefined;

访问器属性不能直接定义，必须使用defineProperty()或defineProperties来定义：如下

function Person(name,age) { this.name = name; this._age = age; if (typeof Person._getName === "undefined"){ Person.prototype.getName = function () { return this.name; }; Person._getName = true; }}var person = new Person("Rose",18);Object.defineProperty(person,"age",{ get:function () { return this._age; }, set:function (age) { this._age = age; }});person.age = 20;console.log(person.age);//20//person.age=20是使用set方法将20赋值给_age，person.age是使用get方法将_age的读取出来console.log(person._age);//20

获取所有的属性和属性的特性

使用Object.getOwnPropertyNames(object)方法可以获取所有的属性；

使用Object.getOwnPropertyDescriptor(object,property)方法可以取得给定属性的特性；

function Person(name,age) { this.name = name; this._age = age; if (typeof Person._getName === "undefined"){ Person.prototype.getName = function () { return this.name; }; Person._getName = true; }}var person = new Person("Rose",18);Object.defineProperty(person,"age",{ get:function () { return this._age; }, set:function (age) { this._age = age; }});console.log(Object.getOwnPropertyNames(person));//["name", "_age", "age"]console.log(Object.getOwnPropertyDescriptor(person,"age"));//{enumerable: false, configurable: false, get: function, set: function}

对于数据属性，可以取得：configurable,enumberable,writable和value；

对于访问器属性，可以取得：configurable,enumberable,get和set；

继承机制实现

对象冒充

function Father(name) { this.name = name ; this.getName = function () { return this.name; }}function Son(name,age) { this._newMethod = Father; this._newMethod(name); delete this._newMethod; this.age = age; this.getAge = function () { return this.age; }}var father = new Father("Tom");var son = new Son("Jack",18);console.log(father.getName());//Tomconsole.log(son.getName());//Jack//继承父类getName()方法console.log(son.getAge());//18

多继承（利用对象冒充可以实现多继承）

function FatherA(name) { this.name = name ; this.getName = function () { return this.name; }}function FatherB(job) { this.job = job; this.getJob = function () { return this.job; }}function Son(name,job,age) { this._newMethod = FatherA; this._newMethod(name); delete this._newMethod; this._newMethod = FatherB; this._newMethod(job); delete this._newMethod; this.age = age; this.getAge = function () { return this.age; }}var fatherA = new FatherA("Tom");var fatherB = new FatherB("Engineer");var son = new Son("Jack","Programmer",18);console.log(fatherA.getName());//Tomconsole.log(fatherB.getJob());//Engineerconsole.log(son.getName());//Jack//继承父类FatherA的getName()方法console.log(son.getJob());//Programmer//继承父类FatherB的getJob()方法console.log(son.getAge());//18

call()方法

function Father(name) { this.name = name ; this.getName = function () { return this.name; }}function Son(name,job,age) { Father.call(this,name); this.age = age; this.getAge = function () { return this.age; }}var father = new Father("Tom");var son = new Son("Jack","Programmer",18);console.log(father.getName());//Tomconsole.log(son.getName());//Jack//继承父类getName()方法console.log(son.getAge());//18

多继承（利用call()方法实现多继承）

function FatherA(name) { this.name = name ; this.getName = function () { return this.name; }}function FatherB(job) { this.job = job; this.getJob = function () { return this.job; }}function Son(name,job,age) { FatherA.call(this,name); FatherB.call(this,job); this.age = age; this.getAge = function () { return this.age; }}var fatherA = new FatherA("Tom");var fatherB = new FatherB("Engineer");var son = new Son("Jack","Programmer",18);console.log(fatherA.getName());//Tomconsole.log(fatherB.getJob());//Engineerconsole.log(son.getName());//Jack//继承父类FatherA的getName()方法console.log(son.getJob());//Programmer//继承父类FatherB的getJob()方法console.log(son.getAge());//18

apply()方法

function Father(name) { this.name = name ; this.getName = function () { return this.name; }}function Son(name,job,age) { Father.apply(this,new Array(name)); this.age = age; this.getAge = function () { return this.age; }}var father = new Father("Tom");var son = new Son("Jack","Programmer",18);console.log(father.getName());//Tomconsole.log(son.getName());//Jack//继承父类getName()方法console.log(son.getAge());//18

多继承（利用apply()方法实现多继承）

function FatherA(name) { this.name = name ; this.getName = function () { return this.name; }}function FatherB(job) { this.job = job; this.getJob = function () { return this.job; }}function Son(name,job,age) { FatherA.apply(this,new Array(name)); FatherB.apply(this,new Array(job)); this.age = age; this.getAge = function () { return this.age; }}var fatherA = new FatherA("Tom");var fatherB = new FatherB("Engineer");var son = new Son("Jack","Programmer",18);console.log(fatherA.getName());//Tomconsole.log(fatherB.getJob());//Engineerconsole.log(son.getName());//Jack//继承父类FatherA的getName()方法console.log(son.getJob());//Programmer//继承父类FatherB的getJob()方法console.log(son.getAge());//18

原型链方法

function Father() {}Father.prototype.name = "Tom";Father.prototype.getName = function () { return this.name;};function Son() {}Son.prototype = new Father();Son.prototype.age = 18;Son.prototype.getAge = function () { return this.age;};var father = new Father();var son = new Son();console.log(father.getName());//Tomconsole.log(son.getName());//Tom//继承父类FatherA的getName()方法console.log(son.getAge());//18

混合方式（call()+原型链）

function Father(name) { this.name = name;}Father.prototype.getName = function () { return this.name;};function Son(name,age) { Father.call(this,name); this.age = age;}Son.prototype = new Father();Son.prototype.getAge = function () { return this.age;};var father = new Father("Tom");var son = new Son("Jack",18);console.log(father.getName());//Tomconsole.log(son.getName());//Jack//继承父类Father的getName()方法console.log(son.getAge());//18

多态机制实现

function Person(name) { this.name = name; if (typeof this.getName !== "function"){ Person.prototype.getName = function () { return this.name; } } if (typeof this.toEat !== "function"){ Person.prototype.toEat = function (animal) { console.log( this.getName() + "说去吃饭："); animal.eat(); } }}function Animal(name) { this.name = name; if (typeof this.getName !== "function"){ Animal.prototype.getName = function () { return this.name; } }}function Cat(name) { Animal.call(this,name); if (typeof this.eat !== "function"){ Cat.prototype.eat = function () { console.log(this.getName() + "吃鱼"); } }}Cat.prototype = new Animal();function Dog(name) { Animal.call(this,name); if (typeof this.eat !== "function"){ Dog.prototype.eat = function () { console.log(this.getName() + "啃骨头"); } }}Dog.prototype = new Animal();var person = new Person("Tom");person.toEat(new Cat("cat"));//Tom说去吃饭：cat吃鱼person.toEat(new Dog("dog"));//Tom说去吃饭：dog啃骨头

以上这篇老生常谈javascript的面向对象思想就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。