TodoStore.js

var events = new EventEmitter();
var CHANGE_EVENT = 'CHANGE';

var todos = {};

var TodoStore = {
  
  addChangeListener: function(callback) {
    events.addListener(CHANGE_EVENT, callback);
  },
  removeChangeListener: function(callback) {
    events.removeListener(CHANGE_EVENT, callback);
  }
  /*
   * In this case, do not provide emitChange as 
   * a publicly available method in your store
    emitChange: function() {
      this.emit(StoreConstants.CHANGE);
    },
   */
};

TodoStore.dispatchToken = AppDispatcher.register((action) => {
  if (action.type === ActionTypes.TODOS_LOADED) {
    todos = action.todos
    events.emit(CHANGE_EVENT);
  }

});

module.exports = TodoStore;