Async Fetch Pipe

asyng-pipe.js

const fetch = require('node-fetch');
/*
An async pipe, each function we pass to the pipe 
will be called with the result from the previous one. 
Since this result will be a promise we 
will await for the promise to resolve first. 
*/
const pipe = (...fns) => x => (
  fns.reduce(async (y, f) => f(await y), x)
)

// The async pipe let us write functions synchronously without the need of using Promise

const fetchData = async url => fetch(url)

const extractJSON = async response => {
  //Maybe we want to set the response to 404 if nothing is returned
  if (!response && typeof response.json === 'function') return

  try {
    const json = await response.json()
    return json
  } catch(err) {
    console.log('ERROR', err)
    // Return 500 if error
    return 500
  }
}

const mapJson = async json => {
  //Check if there is an error
  if (json === 500) return 500

  //Check if there is data
  if(!json.data && !json.data.length) return

  try {
    json.data.map((user, i) => console.log(`User ${i} name is ${user['first_name']}`))
  } catch (err) {
    console.log('ERROR', err)
    // Return 500 if error
    return 500
  }
}

// Compose the pipe

const getUserNames = url => pipe(
  fetchData,
  extractJSON,
  mapJson
)(url)

console.log('Log user names ', getUserNames('https://reqres.in/api/users?page=2'))
// This logs:
// User 0 name is Eve
// User 1 name is Charles
// User 2 name is Tracey