wapo

wapo.js

const lib = {
  findUser: () => new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve({name: 'ricky', content: 'z-z'})
    }, 1)
  }),
  getUsers: (users = []) => new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve([
        ...users,
        {name: 'bob', content: 'a-b'},
        {name: 'jason', content: '1-2'}
      ])
    }, 400)
  }),
  mapIdsToUsers: (users = []) => new Promise((resolve, reject) => {
    setTimeout(() => {
      if (users.length < 1) {
        reject()
      } else {
        const mappedIds = users.map((user, i) => Object.assign({}, user, {index: i}))
        resolve(mappedIds)
      }
    }, 400)
  }),
  reduceUserContent: (users = []) => new Promise((resolve, reject) => {
    setTimeout(() => {
      if (users.length < 1) {
        reject()
      } else {
        const cleanedData = users.reduce((acc, {content}) => {
          return [...acc, ...content.split('-')]
        }, [])
        resolve(cleanedData)
      }
    }, 400)
  })
}

let users = []
let err

function solution() {
  lib.findUser().then((user) => {
    users.push(user)
  })
  return new Promise((resolve, reject) => {
    lib.getUsers(users).then(res => {
      users = res
      lib.mapIdsToUsers(res).then(res => {
        users = res
        lib.reduceUserContent(users).then(res => {
          resolve(res)
        }).catch(reject)
      }).catch(reject)
    }).catch(reject)
  })
}

solution().then(r => {
  // r will be [z, z, a, b, 1, 2]
  // we can modify the problem to return something "less intuitive"
  // since we never want to write code like this...
})