Frog.js

class Frog {
  constructor(name, gender) {
    this.name = name
    this.gender = gender
  }
  
  jump() {
    console.log('jumped')
  }
}

class Toad {
  constructor(habitat, name, gender) {
    this.habitat = habitat
    this.frog = new Frog(name, gender)
  }
}

const mikeTheToad = new Toad('land', 'mike', 'male')