Prototypes and prototype chains in JavaScript

1. What is a prototype? What is the prototype chain?

A prototype is a prototype object that represents the relationship between types;

The prototype chain refers to the inheritance between objects in JavaScript by pointing to the parent class object through the prototype object, until it points to object objects, thus forming a chain that the prototype points to, which is called the prototype chain.

Example:

Student-->person-->object: The student inherits This kind, the person this class inherits the object class;

<span style= "FONT-SIZE:14PX;" >
  var person=function () {
      this.age= "Anonymous"
  };    var student=function () {};    Creates an inheritance relationship, prototype executes an instance object of person    student.prototype=new person  ();
</span>  

Five prototype rules:

1, all reference types (arrays, objects, functions), all have object attributes, you can freely extend the properties (except "null");

2, all reference types have a _proto_ attribute, called implicit prototype, the attribute value is an ordinary object;

3, all functions, have a prototype attribute, called explicit prototype, attribute value is a common object;

4. The _proto_ property of all reference types, the value of the prototype attribute that points to its constructor;

<! DOCTYPE html>"Utf-8"> <title></title> <script>//All reference types have object properties            varobj = {}; OBJ.A= -; vararr = []; ARR.A= -; function fn () {} Fn.a= -; //All reference types have an implicit prototypeConsole.log (obj.__proto__);            Console.log (arr.__proto__);                        Console.log (fn.__proto__); //all functions have a prototype propertyConsole.log (Fn.prototype); //All reference types, the __proto__ property value points to the "prototype" property value of its constructorConsole.log (obj.__proto__ = = =Object.prototype); </script> 
5, when trying to get a property of an object, if not, will look for it in the _proto_, that is, go to its constructor prototype.
<! DOCTYPE html>"Utf-8"> <title></title> <script>//constructor Functionfunction Foo (name,age) { This. Name =name; } Foo.prototype.alerName=function () {alert ( This. Name); }            //Create an instance            varf =NewFoo ('Zhangsan'); F.printname=function () {Console.log ( This. Name); }            //TestF.printname ();        F.alername (); </script> 
Again for example:
The dog class inherits the animal class and then owns the animal eat method (an example of very low)
<script type= "Text/javascript" >        function Animal () {            this.eat = function () {                console.log ("Animal eat ");            }        }        function Dog () {            This.bark = function () {                console.log ("Dog bark")            }        }        dog.prototype = new Animal () ;        var Hashiqi = new Dog ();        Hashiqi.eat ();　　　Animal eat        hashiqi.bark (); Dog Bark    </script>
Examples of close combat (an example of a package DOM query):
Be very careful about the location of JavaScript <!            DOCTYPE html>
Prototypes and prototype chains in JavaScript