$.Deferred vs new Promise vs Callbacks - be careful you are not rebuilding the hell

gistfile1.js

// consider the following code

function getInfoDef() {
  var result = {something: 'static'};
  var def = $.Deferred(); 
 
  $.ajax('/some-url').then(function(data) {
    result.also = data.dynamic; 
    def.resolve(result);
  }).fail(def.reject.bind(def)); 
  
  return def.promise();
}

// if you are like me (half a year ago) you probably think this is just fine
// however, lets rewrite the same using ES6 Promises

function getInfoES6() {
  return new Promise(function(resolve, reject) {
    var result = {something: 'static'};
    $.ajax('/some-url').then(function(data) {
      result.also = data.dynamic; 
      resolve(result);
    }).fail(reject); 
  });
}

// notice the extra level of indentation?
// does it remind you of callback hell?
// that's because it still is the same inversion control

function getInfoCB(callback) {
    var result = {something: 'static'};
    $.ajax('/some-url').then(function(data) {
      result.also = data.dynamic; 
      callback(null, result);
    }).fail(callback); 
  });
}

// this is how you should do it
function createThingy(remoteData) {
  return {
    something: 'static',
    also: remoteData.dynamic
  }
}

function getInfo() {
  return $.ajax('/some-url').then(createThingy);
}