How to create a JavaScript class in ES6 ?

A class describes the contents of objects belonging to it: it describes a set of data fields (called instance variables) and it defines the operations on those fields (called methods). In order words, it is also defined as the collection or a group of object that contains object data types along with some methods in it. You can create a JavaScript class by using a predefined keyword named class before the class name. We will show you some examples below to illustrate how it works.

Let us have a look over the following syntax section which illustrates how to declare a class in JavaScript:

Syntax:

class class_name { // body of the class // Here methods and object data types could be defined... }

Creating an object of a class can be accomplished by using the new keyword and calling the constructor of that class (at the time of object instantiation). A constructor is declared by using the predefined keyword constructor. Constructors can be of any type, such as default constructors and parameterized constructors. As we can see here, we use a constructor to initialize and declare a variable. However, there can only be one constructor per class, and it can be parameterized or defaulted and further note point would be that the constructor doesn't have any return type.  

Syntax:

class name { constructor(a, b, c) { // Initialize the class variable } }

Example 1:

class Geeks {  // Constructor  constructor(num1, num2) {  console.log("Inside Constructor");  // Initialize class variable  this.num2 = num2;  this.num1 = num1;  } } // Initialize the class object let obj = new Geeks(1, 2); console.log(obj.num1); console.log(obj.num2); 

Output:

Inside Constructor 1 2

Example 2:

class Geeks {  constructor(num1, num2) {  this.num2 = num2;  this.num1 = num1;  }  add() {  console.log(  this.num1 + "+" + this.num2 +   "=" + (this.num1 + this.num2));  } } let obj = new Geeks(1, 2); obj.add(); 

Output:

1+2=3