code-splitting-3.js

// createStore.js
const reducer = combine(reducerRegistry.getReducers())
const store = createStore(reducer)
                          
reducerRegistry.setChangeListener(reducers => {
  store.replaceReducer(combine(reducers))
})

// data/jobs.js
export default function reducer(state = initialState, action = {}) {
  switch (action.type) {
    case HYDRATE:
      return action.state.jobs || state
    case ADD_JOB:
      return [...state, { ...action.payload, id: jobId += 1 }]
    case REMOVE_JOB:
      return state.filter(job => job.id !== action.payload)
    default:
      return state
  }
}

reducerRegistry.register('jobs', reducer)