JS's encapsulation, inheritance, polymorphism

JS is a very flexible language, do not talk about polymorphism (or that it is polymorphic)
Packaging
Concept:
Closed part, no direct access to the outside world
Indirect access to private parts through open sections
Example:
Not encapsulated: All properties of the constructor are open

function Girl (NAME,BF) {    this. Name = name;      this. bf = BF;} var New Girl ("Lin Daiyu", "Jiabaoyu" + "Love" + GIRL.BF); // lin Daiyu love Jia Baoyu

Encapsulation: Encapsulates part of a property to be accessed by a public interface

 function   Girl (NAME,BF) { var  secret = BF;     this . Name = name;  this . Showlove = function   () { return   secret;  var  girl = new  Girl ("Lin Daiyu", "Jia Baoyu") Span style= "color: #000000;" ); alert (girl.name  + "Love" + Girl.secret); //  Lin Daiyu love Undefined,secret not accessible  alert (girl.name + "Love" + Girl.showlove ()); //  Lin Daiyu love Jia Baoyu, access to private properties indirectly through the open section  

Summary: Complete encapsulation of private properties with closures
Inherited
First, the prototype inheritance

//the core of the prototype chain is __proto__  functionDog () { This. Bark =function() {alert ("Wangwang")      }  }  functionHashiqi () {} Hashiqi.prototype=NewDog (); varDog1 =NewHashiqi (); Dog1.bark ();//WangwangHashiqi.prototype.bark=function() {alert ("Wuwu"); }  varDOG2 =NewHashiqi (); Dog2.bark ();//Wuwu  varDog3 =NewDog (); Dog3.bark ();//Wangwang

Second, the object impersonating
Temp variable

function Parent () {} function Child () {    this. temp = Parent;       This . Temp ();     Delete  This . temp;}

Call () and apply ()

function Parent () {} function Child () {   Parent.call (this, var1,var2 ...)    // parent.apply (This,[var1,var2 ...])}

Iii. copying and inheriting

Object.prototype.extend =function(obj) { for(varKeyinchobj) {        if( This[key]==undefined) {             This[key]=Obj[key]; }    }}varCat = {color: "Yellow", climb:function() {alert ("I will climb the tree");}}varTiger = {color: "Yellow and black"}tiger.extend (cat); tiger.climb ();//I can climb trees .alert (Tiger.color);//Yellow and Black

Iv. Mixed inheritance

Static methods

// this is a constructor and an object function Bird () {    this. wings=2;       This function () {        alert ("I Will Fly");    }}// This is a static method of the bird object and belongs to this object function only   () {   alert ("Eat Bug")}varnew Bird ();   Bird instance, cannot access eat ()

JS's encapsulation, inheritance, polymorphism