Class-based OOP without "class" Raw

javascript.js

// base class
// - class is also constructor
// - private properties are local variables that are not exposed (true private)
// - public properties are object's properties
const Animal = (age, sex) => ({
  greet: () => '',
  getAge: () => age,
  getSex: () => sex ? 'male' : 'female'
})

// subclass: Dog (extends Animal)
const Dog = (...args) => {
  const greet = () => ''
  
  return {
    // overriding method: greet
    greet,
    
    // own method: bark
    bark: greet,
    
    // inherit from Animal
    __proto__: Animal(...args)
  }
}

// subclass: Human
const Human = (age, sex, name) => ({
  // overriding method: greet
  greet: () => `Greetings, I'm ${name}`,
  
  getName: () => name,
  
  // call super-constructor
  __proto__: Animal(age, sex)
})