how to instantiate a class in javascript code example

Example 1: node js class

//Node js class: Here a quick code example

// Basic class
class Rectangle {
  
  // Constructor
  constructor(height, width) {
    // Member variables
    this.height = height;
    this.width = width;

    // Access static member variable
    Rectangle.count++;
  }
  
  // Getter
  get area() {
    return this.calcArea();
  }
  
  // Method
  calcArea() {
    return this.height * this.width;
  }

  // Static method
  static calcArea(width, height) {
    return width * height;
  }
}

// Static member variable
Rectangle.count = 0;


// Class instantiation
const square = new Rectangle(10, 10);

// Access member variable
console.log(square.height, square.width); // 10 10

// Call getter
console.log(square.area);	// 100

// Call method
console.log(square.calcArea()); // 100


// Access static member variable
console.log(Rectangle.count); // 1

// Call static method
console.log(Rectangle.calcArea(15, 15));  // 225

Example 2: how to create instance of class in javascript

class Hello {
	person(name){
    	this.name = name;
    }
  	// Constructor - Important except for JSX
    constructor(name){
    	this.person(name);
        console.log(`Hello ${this.name}`);
    }
}

const helloInstance = new Hello('john doe');