Promises chaining that solves "callbacks hell"

promises-chaining.js

'use strict';


var Promise = require('promise');


function build() {
  return new Promise(function(fulfill, reject) {
    fulfill('zero');
  });
}


build().then(function(result) {
  console.log(result); // `zero`
  return 'one';

}).then(function(result) { // `one`
  console.log(result);
  return ['apple', 'banana', 'pear'];

}).then(function(result) {
  console.log(result); // `['apple', 'banana', 'pear']`

  // Returning anything inside promise fulfillment/rejection
  // callbacks, creates a promise for you automatically
  // offering executions chaining.

  // This is exactly how promises are approaching to
  // solve so popular "callbacks hell".
  return {
    name: 'Nik Sumeiko',
    website: 'http://teamnik.org'
  };

}).then(function(result) {
  console.log(result); // `{ name: 'Nik Sumeiko', website: 'http://teamnik.org' }`
  return build();

}).then(function(result) {
  console.log(result); // `zero`
  
});