JSFiddle - React, Tailwind, and code Playground

JavaScript

class Shape { 
    constructor(x, y) {
        this.x = x;
        this.y = y;
    }
    area() {}
}
//P = r*r*PI
  class Circle extends Shape {
    area() {
      return this.x * this.x * Math.PI;
    }
  }

  //P = a*h/2
  class Triangle extends Shape {
    area() {
        return this.x * this.y/2;
    }
  }
  //P = a*h
  class Parallelogram extends Shape {
    area() {
        return this.x * this.y
    }
  }

  //P = a*a
  class Square extends Shape {
    area() {
        return this.x * this.x
    }
  }

  //P = a*b
  class Rectangle extends Shape {
    area() {
        return this.x * this.y
    }
  }
  
var c = new Circle(2);

console.log("P = r*r*PI => " + c.area());

var t = new Triangle(3,2);
console.log(t.area());

var p = new Parallelogram(3,2);
console.log(p.area());

var s = new Square(2);
console.log(s.area());

var r = new Rectangle(3,2);
console.log(r.area());