Provide an initial state object for the store, works in the same way as reacts getInitialState method. If omitted an empty object is provided as state for the store.

fluxapp.registerStore('users', {
  getInitialState: function() {
    return {
      users: []
    };
  },
  
  getAll: function() {
    return this.state.users;
  }
});

👍

On to addChangeListener(cb)