inheritance.js

class Person {
  constructor (firstName, lastName, birthday) {
    this.firstName = firstName
    this.lastName = lastName
    this.birthday = birthday
  }
  sayHello () {
    return `My name is ${this.firstName}`
  }
}

class SuperGirl extends Person {
  constructor (firstName, lastName, birthday, superpowers) {
    super(firstName, lastName, birthday)
    this.gender = 'female'
    this.superpowers = superpowers
  }
  fly () {
    return 'I can fly'
  }
}

const sg = new SuperGirl('Kara', 'Zor-El', 1554143709, [
  'flying', 'heat vision', 'strength'
])
console.log(sg.sayHello(), sg.fly())