Object Oriented Programming in JavaScript: Part 2

Introduction

 

JavaScript is a prototype-based programming style of object-oriented programming in which classes are not present. 

 

It can support OOP because it supports inheritance through prototyping as well as properties and methods.

 

Object-Oriented Programming in JavaScript is known as prototype-based programming. 

 

I have already explained the basics of OOP in JavaScript so it would be great if you go through with the following link.

 

Object-Oriented Programming in JavaScript: Part 1

 

In the last article we already discussed the following things:

• Classes in JavaScript
• Constructor in JavaScript
• Properties in JavaScript
• Object of JavaScript classes

Now we will learn methods in JavaScript classes.

 

Use the following procedure to create a sample to help understand how to create methods in JavaScript classes.

1. Creating Class in JavaScript
    
   The following syntax is used for declaring a class in JavaScript:

   function Emp(NAME) {
       alert("EMP Instantiated");
       this.NAME = NAME;
   }

   Here Emp can act as a class in JavaScript and this.NAME would act as a property.
    
   The body of Emp acts as the constructor and is called as soon as we create an object of the class.
    
2. Defining Methods of JavaScript classes

   Emp.prototype.Fun1 = function ()
   {
      alert("EMP NAME is :" + this.NAME );
   }

   We can create a method using the syntax above. Here Fun1 would act as a method of the EMP class.
    
    
3. Calling functions

   var Emp1 = new Emp('DEVESH');
   var Emp2 = new Emp('ROLI');
   
   Emp1.Fun1();
   Emp2.Fun1()
   }

   Here we created two instances of EMP, EMP1 and EMP2 and passed a parameter to the constructor to assign a NAME Property.
    
   Using EMP1.Fun1() and EMP2.Fun1() we are calling the functions.
    
   We have defined an alert inside this function:
    
    
4. Running the code
    
   After running the code we will get two alerts, each for EMP1.fun1() and Emp2.Fun1();
    
    
5. Other ways to create JavaScript objects
    
   We can create an object in JavaScript in the following way also:

   var EMP = {
       firstName:"ROLI",
       lastName:"GUPTA",
       age:28,
       sex:"F"
   };
6. Accessing EMP objects
    
    

   alert("EMP NAME: " + EMP.firstName + " " + EMP.lastName + " EMP AGE: " + EMP.age + " EMP SEX : " + EMP.sex);
   
   lete Code
   
   var EMP = {
      firstName: "ROLI",
      lastName: "GUPTA",
      age: 28,
      sex: "F"
   };
   alert("EMP NAME: " + EMP.firstName + " " + EMP.lastName + " EMP AGE: " + EMP.age + " EMP SEX : " + EMP.sex);

7. Running the code
    
    
8. Defining Methods

   var EMP = {
   firstName: "ROLI",
   lastName: "GUPTA",
   age: 28,
   sex: "F",
   fullName: function () { return this.firstName + " " + this.lastName }
   };
   alert("Full name is: "+EMP.fullName());

   We have defined the fullName method inside the EMP class.
    
   It returns the join of fname and lname.
    
   Running the code
    

Conclusion

 

This document explains methods in JavaScript classes.

 

Previous article: Object-Oriented Programming in JavaScript: Part 1