privateWorlds.js

const preparePeopleWithFavoriteColor = (color) => {
  const _people = []
  
  return {
    getPeople() {
      return _people
    },
    addPeople(people) {
      _people.push(...people)
    },
    addPerson(person) {
      _people.push(person)
    },
    gather(people) {
      if (Array.isArray(people)) {
        people.forEach((person) => {
          if (color === person.favoriteColor) {
            _people.push(person)
          }
        })
      }
    },
  }
}

const peopleWhoLoveRed = preparePeopleWithFavoriteColor('red')

axios
  .get('https://someapi.com/peoples')
  .then((response) => {
    const people = response.data.result
    if (people.length) {
      peopleWhoLoveRed.gather(people)
    }
    return axios
      .get('https://someapi.com/other-peoples')
      .then((response) => {
        const morePeople = response.data.result
        if (morePeople.length) {
          everyoneWhoLovesRed.gather(morePeople)
        }
        return
      })
      .then(() => {
        // finally, add me last because i love red too
        peopleWhoLoveRed.addPerson({
          nickName: 'jsmanifest',
          favoriteColor: 'red',
        })
        return axios.post('https://api.redlovers.com/v1/subscribers/', {
          people: peopleWhoLoveRed.getPeople(),
        })
      })
  })
  .catch((error) => {
    console.error(error)
  })