Promise utilities

promise-serial.js

import Promise from 'bluebird'

Promise.serial = (input, initialPromise) =>
  Promise.reduce(
    input,
    (previousResult, fn) => fn(previousResult),
    initialPromise
  );

Promise.prototype.serial = function serial(input) {
  return Promise.serial(input, this);
}

/*
const getUserName = id =>
  Promise.serial([
    response => Promise.resolve(response.json),
    json => json.userName,
  ], fetch(`https://example.com/user/${id}`))

getUserName(0).then(userName => console.log(userName)); // => jack
*/

/*
const getUserName = id =>
  fetch(`https://example.com/user/${id}`)
    .serial([
      response => Promise.resolve(response.json),
      json => json.userName,
    ]);

getUserName(0).then(userName => console.log(userName)); // => jack
*/