Code that voilates OCP

violates-ocp.js

class AreaCalculator {
  constructor (shapes) {
    this.shapes = shapes
  }

  sum () {
    return this.shapes
      .map((shape) => {
        if (shape instanceof Circle) {
          return 2 * Math.PI * Math.pow(shape.radius, 2)
        }
        else if (shape instanceof Square) {
          return Math.pow(shape.length, 2)
        }
      })
      .reduce((totalArea, currentArea) => {
        return totalArea + currentArea
      }, 0)
  }
}