js如何实现继承

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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function teacher(name){  
    this.name = name;  
}  
teacher.prototype.sayName = function(){  
    console.log("name is "+this.name);  
}  
var teacher1 = new teacher("xiaoming");  
teacher1.sayName();  
  
function student(name){  
    this.name = name;  
}  
student.prototype = new teacher()  
var student1 = new student("xiaolan");  
student1.sayName();  
//  name is xiaoming  
//  name is xiaolan  


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