Object composition - class part 2

Duck_class2.js

class Swimmable {
  constructor() {
    this.speed = 1
  }

  swim() {
    console.log(`Swam ${this.speed} meter(s)`)
  }
}

class Quackable {
  constructor() {
    this.speed = 1
  }

  quack() {
    console.log("Quack!".repeat(this.speed))
  }
}

// Without DI
class Duck {
  #swimmable
  #quackable

  constructor() {
    this.#swimmable = new Swimmable()
    this.#quackable = new Quackable()

    this.#swimmable.speed = 2
    this.#quackable.speed = 3
  }

  swim() {
    this.#swimmable.swim()
  }

  quack() {
    this.#quackable.quack()
  }
}

const donald = new Duck()
donald.swim() // Swam 2 meter(s)
donald.quack() // Quack!Quack!Quack!

// With DI
class Duck2 {
  #swimmable
  #quackable

  constructor(swimmable, quackable) {
    this.#swimmable = swimmable
    this.#quackable = quackable

    this.#swimmable.speed = 2
    this.#quackable.speed = 3
  }

  swim() {
    this.#swimmable.swim()
  }

  quack() {
    this.#quackable.quack()
  }
}

const swimmable = new Swimmable()
const quackable = new Quackable()
const donald2 = new Duck2(swimmable, quackable)
donald2.swim() // Swam 2 meter(s)
donald2.quack() // Quack!Quack!Quack!