JS继承的多种方式

 

1. 原型链

   function SuperType(){
       this.property=true;
   }
   SuperType.prototype.getSuperValue=function(){
       return this.property;
   }
   function SubType(){
       this.subProperty=false;
   }
   SubType.prototype=new SuperType();//给SubType换个新原型

   //不能通过使用对象字面量创建原型方法，会导致重写原型链
   SubType.prototype={
       getSubValue:function(){},
       someOther:function(){}
   }
   //以上写法不可取

2. 借用构造函数

   function SuperType(){
       this.colors=["red","blue"];
   }
   function SubType(){
       SuperType.call(this);
       this.age=30;
   }

3. 组合继承（最常用的继承方式，结合方法一和方法二）

   function SuperType(name){
       this.name=name;
       this.colors=['red','blue'];
   }
   SuperType.prototype.sayName=function(){
       alert(this.name);
   }
   function SubType(name,age){
       SuperType.call(this,name);
       this.age=age;
   }
   SubType.prototype=new SuperType();
   SubType.prototype.sayAge=function(){
       alert(this.age);
   }

4. 原型式继承

   function object(o){
       function F(){}
       F.prototype=o;
       return new F();
   }
   var person={name:'frank',friends:['andy','anmi']}
   var anoPerson=object(person);
   anoPerson.friends.push('greg');
   alert(person.friends);//['andy','anmi','greg']
   //实现的是浅复制

   ES6规范化：用Object.create()
   var anoPerson=Object.create(person,{
       name:{
           value:'test'
       }
   });

5. 寄生式继承

   function createAno(original){
       var clone=object(original);//object是一个能返回新对象的函数
       clone.sayHi=function(){
           alert('hi');
       }
       return clone;
   }
   var person={name:'greg'}
   var anoPerson=createAno(person); 

6. 寄生组合式继承

   function inheritPrototype(subType,superType){
       var prototype=object(superType.prototype);
       prototype.constructor=subType;
       subType.prototype=prototype;
   }
   function SuperType(name){
       this.name=name;
   }
   SuperType.prototype.sayName=function(){
       alert(this.name);
   }
   function SubType(name,age){
       SuperType.call(this,name);
       this.age=age;
   }
   inheritPrototype(SubType,SuperType);
   SubType.prototype=function(){
       alert(this.name);
   }