Introduction to several methods of prototypal inheritance

Prototype inheritance

Parent:

    function Parent(name){
        this.name=name;
    }
    Parent.prototype.sayHello=function(){
        console.log("Hello,"+this.name);
    }

1. Prototype chain inheritance

   function Kid(){};
   Kid.prototype=new Parent("who");
   
   var k=new Kid();
   console.log(k.name); //who
   console.log(k.sayHello()); //Hello,who

   Disadvantages:Unable to pass parameters to the parent when creating an instance

2. ##Construction inheritance

   function Kid(name){
       Parent.call(this,name);
   };
   
   var k=new Kid("who");
   console.log(k.name); //who
   console.log(k.sayHello()); //error

   Disadvantages:Unable to obtain parent prototype chain attributes

3. Instance inheritance

   function Kid(name){
       var p=new Parent(name);
       return p;
   };
   
   var k=new Kid("who");
   console.log(k.name); //who
   console.log(k.sayHello()); //Hello,who

   Disadvantages: The instance is the instance of the parent

4. Copy inheritance

   function Kid(name){
       var p=new Parent(name);
       for(var item in p){
           Kid.prototype[item]=p[item];
       }
   }
   
   var k=new Kid("who");
   console.log(k.name); //who
   console.log(k.sayHello()); //Hello,who

   Disadvantages: Taking up too much memory

5. Combined inheritance

   function Kid(name){
       Parent.call(this,name);
   }
   Kid.prototype=new Parent();
   
   var k=new Kid("who");
   console.log(k.name); //who
   console.log(k.sayHello()); //Hello,who

   Disadvantages: The parent class constructor is called twice

6. Parasitic Combination Inheritance

   function Kid(name){
       Parent.call(this,name);
   }
   (function(){
       var p=function(){};
       p.prototype=Parent.prototype;
       Kid.prototype=new p();
   })()

   Disadvantages: The writing method is more cumbersome

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