returnRefThenCall.js

/*
 * This code was inspired by AngularJS $resource object
 * on which you can do something like this:
 
 var users = User.query(function() {
    console.log(users[0]);
 });
 
 * Source code: https://github.com/angular/angular.js/blob/master/src/ngResource/resource.js#L76
 */

// something that, differently than other languages, you can easily reach with JS
var returnRefThenCall = function returnRefThenCall(callback) {

  var value,
    // create and execute the promise
    p = new Promise(function(fullfill, reject) {
      // execution phase 1
      value = ['my', 'name', 'is', 'foo', 'bar'];
      fullfill();
    })
    .then(function() {
      // execution phase 3
      callback();
    });

  // execution phase 2
  // first return the value
  return value;
};

// the array is returned
var array = returnRefThenCall(
  // after returnAndCall returns it calls the callback function 
  // and by that time you already have the `array` set
  function() {
    console.log(array.join(','));
  });