'barking dog'

es5.js

function Animal(name) {
  this.name = name
}

Animal.prototype.getName = function() {
  return this.name
}


function Dog(name) {
  Animal.apply(this, arguments)
}

Dog.prototype = Object.create(Animal.prototype)
Dog.prototype.constructor = Dog

Dog.prototype.bark = function() {
  return 'Dog ' + this.name + ' is barking'
}

const dog = new Dog('Aban')

console.log( dog.getName() === 'Aban' )
console.log( dog.bark() === 'Dog Aban is barking' );

es6.js

class Animal {
  constructor(name) {
    this.name = name
  }

  getName() {
    return this.name
  }

}

class Dog extends Animal {
  bark() {
    return `Dog ${this.name} is barking`;
  }
}


const dog = new Dog('Aban')

console.log( dog.getName() === 'Aban' )
console.log( dog.bark() === 'Dog Aban is barking' );

это желательно, но не обязательно, это не ошибка