Result.js

const CarVisitor = {
  accelerate: function(visitor) {
    console.log(`Yeah! I am driving a ${visitor.name}.`)
  },
  
  brake: function(visitor) {
    console.log(`Brakes failed in ${visitor.name}.`)
  }
}

class Car {
  operate(carVisitor) {}
}

class Sedan extends Car {
  constructor(name) {
    super()
    this.name = name
  }
  
  operate(visitor=CarVisitor) {
    visitor.accelerate(this)
  }
}

class Hatchback extends Car {
  constructor(name) {
    super()
    this.name = name
  }
  
  operate(visitor=CarVisitor) {
    visitor.brake(this)
  }
}

const sedan = new Sedan('Sedan')

sedan.operate() // Yeah, I am driving a Sedan.

const hatchback = new Hatchback('Hatchback')

hatchback.operate() // Brakes failed in Hatchback.