OOP Programming in JS

This article applies to ES6 before ...

JavaScript needs to use functions to emulate classes.

function Book (name) {    this. Name = name;       This function () {            returnthis. Name;      }        This function (nname) {             this. Name= nname;      }}

New An Object

var New Book ("C #"); // The new operation here is equivalent to creating a simple object, calling the constructor of the class

Each function has a prototype object on top of it--prototype

var proto = book.prototype;   = "string";   function () {       alert ("Hello");  }   // after defining properties and methods for the prototype, the class that owns the function of the prototype object is also given the property and method       // Eject string       // pop-  up Hello}  

Add a common question

functionAnimal (name) { This. Name =name;  This. Age = 0; }      varA1 =Animal; alert (A1); //eject the entire function body    varA2 = Animal ("Dinglang"); alert (A2); //Eject undefined    varA3 =Newanimal (); Alert (A3);//Eject Object    vara4 =NewAnimal; alert (A4);//Eject Object

Class modification, extension (emphasis, difficulty)

//1. If I want to implement a simple addition calculation            var numone = 5;//If defined directly, then the following numone.add (8); execution will error            //If I write this, the following call will not be an error (because at this time the Numone, is a class. Equivalent to the original basic data type, wrapper type in the Java or C # language)            varNumone =NewNumber (5); Numone.add=function(numtwo) {return  This+Numtwo; }              alert (numone.add);//undefined            Alert (Numone.add (8));//It seems correct to write, but it will error--numone.add is not a function            varNumthree =NewNumber (100); //If I want to add a function to the Numthree object now.            //It is implemented directly using the special property of prototype, adding the Add function to all instances of number typeNumber.prototype.add =function(numtwo) {return  This+Numtwo; } alert (Numthree.add (Add (300));//pop-up 100+200+300=600

Implementing Inheritance in JavaScript

 functionClassA (name) { This. Name =name;  This. ShowName =function() {alert ( This. Name); }              }              functionClassB (name) {//1) Implement inheritance using the Newmethod method                //This.newmethod = ClassA;                 //This.newmethod (name);                 //delete This.newmethod;//Release Object                //2) Call the Claasa function and point his context (scope) to this (that is, an instance of the ClassB Class)                //This also allows for inheritance (using call or Apply)Classa.call ( This, name); //classa.apply (This,[name]); } obja=NewClassA ("Operating system"); OBJB=NewClassB ("Composition principle"); Obja.showname (); //Eject "operating system"Objb.showname ();//Eject "Composition principle"          })

OOP Programming in JS