notification_store.js

var Dispatcher = require('the-dispatcher'),
  Immutable = require('immutable'),
  NotificationConstants = require('../constants/notification_constants'),
  UserConstants = require('../constants/user_constants'),
  UploadConstants = require('../constants/upload_constants'),
  StylesheetConstants = require('../constants/stylesheet_constants'),
  makeStore = require('makestore');

/**
 * The Notification Store does nothing but store recent actions
 * in order to power notifications.
 */

var _notifications = Immutable.Set([]);
var _errors = Immutable.List();
var _successes = Immutable.List();

var NotificationStore = makeStore({
  notifications: () => _notifications,
  errors: () => _errors,
  successes: () => _successes,
  dispatcherIndex: Dispatcher.register(action => {
    switch (action.actionType) {
      case NotificationConstants.NOTIFICATION_DISMISS:
        _notifications = Immutable.Set([]);
        break;
      case NotificationConstants.NOTIFICATION_ERROR_DISMISS:
        _errors = _errors.shift();
        break;
      case NotificationConstants.NOTIFICATION_ERROR:
        _errors = _errors.push(action.error);
        break;
      case NotificationConstants.NOTIFICATION_PAYMENT_ERROR:
        _errors = _errors.push(action.error);
        // ASK USER TO PAY
        break;
      case NotificationConstants.NOTIFICATION_UPGRADE_ERROR:
        _errors = _errors.push(action.error);
        // ASK USER TO UPGRADE
        break;
      case NotificationConstants.NOTIFICATION_SUCCESS_DISMISS:
        _successes = _successes.shift();
        break;
      case StylesheetConstants.STYLESHEET_MIGRATE_SUCCESS:
        _successes = _successes.push('Stylesheet successfully migrated to latest version.');
        break;
      case UserConstants.USER_UPDATED:
        _successes = _successes.push('Profile successfully updated.');
        break;
      case UploadConstants.UPLOAD_SET:
        _notifications = _notifications.union(Immutable.Set(
          action.value
            .filter(upload => !upload.complete)
            .map(upload => `Uploading ${upload.dataset}`)));
        break;
      default:
        // avoid emitting changes for other events.
        return true;
    }
    NotificationStore.emitChange(action.actionType);
    return true;
  })
});

NotificationStore.setMaxListeners(1000);
module.exports = NotificationStore;

Very nice implementation of Flux store. Do you call the Utils Ajax requests from the ActionCreators which is called from View (by user) or Component (e.g. ComponentDidMount)?
It would be great to see how your makestore.js looks like.