How to define a class in JavaScript ?

There are two ways to define classes in JavaScript :

Method 1. Class declaration

// Class rectangle
class Rectangle {

	// Constructor
	constructor(height,width)  {
		this.height = height;
		this.width 	= width;
	}

	// Method
	area() {
		return this.width * this.height;
	}
}

Method 2. Class expression

// Class rectangle
let Rectangle = class {

	// Constructor
	constructor(height,width)  {
		this.height = height;
		this.width 	= width;
	}

	// Method
	area() {
		return this.width * this.height;
	}
}

Class instantiation

Whatever the method used to define the class, the class instantiation is done with the new keyword:

const rectangle = new Rectangle(100,200);