javascript面向对象中继承实现

面向对象的基本特征有：封闭、继承、多态。

在javascript中实现继承的方法：

1. 原型链（prototype chaining）

2. call()/apply()

3. 混合方式(prototype和call()/apply()结合)

4. 对象冒充

继承的方法如下：

1、prototype原型链方式：

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functionteacher(name){ this.name=name; } teacher.prototype.sayname=function(){ console.log("nameis"+this.name); } varteacher1=newteacher("xiaoming"); teacher1.sayname(); functionstudent(name){ this.name=name; } student.prototype=newteacher() varstudent1=newstudent("xiaolan"); student1.sayname(); //nameisxiaoming //nameisxiaolan

2、call()/apply()方法

function teacher(name,age){

this.name = name;

this.age = age;

this.sayhi = function(){

alert('name:'+name+", age:"+age);

}

}

function student(){

var args = arguments;

teacher.call(this,args[0],args[1]);

// teacher.apply(this,arguments);

}

var teacher1 = new teacher('xiaoming',23);

teacher1.sayhi();

var student1 = new student('xiaolan',12);

student1.sayhi();

// alert: name:xiaoming, age:23

// alert: name:xiaolan, age:12

3、混合方法【prototype,call/apply】

function teacher(name,age){

this.name = name;

this.age = age;

}

teacher.prototype.sayname = function(){

console.log('name:'+this.name);

}

teacher.prototype.sayage = function(){

console.log('age:'+this.age);

}

function student(){

var args = arguments;

teacher.call(this,args[0],args[1]);

}

student.prototype = new teacher();

var student1 = new student('xiaolin',23);

student1.sayname();

student1.sayage();

// name:xiaolin

// age:23

4、对象冒充

function person(name,age){

this.name = name;

this.age = age;

this.show = function(){

console.log(this.name+", "+this.age);

}

}

function student(name,age){

this.student = person; //将person类的构造函数赋值给this.student

this.student(name,age); //js中实际上是通过对象冒充来实现继承的

delete this.student; //移除对person的引用

}

var s = new student("小明",17);

s.show();

var p = new person("小花",18);

p.show();

// 小明, 17

// 小花, 18