A cache middleware for redux

cache.middleware.js

const cache = store => next => action => {
  // handle FETCH action only
  if (action.type !== 'FETCH') {
    return next(action);
  }

  // check if cache is available
  const data = window['__data'];
  if (!data) {
    // forward the call to live middleware
    return next(action);
  }
  return store.dispatch({ type: 'RECEIVE', payload: { data: `${data} (from cache)` } });
}

export default cache;

live.middleware.js

const live = store => next => action => {
  // handle FETCH action only
  if (action.type !== 'FETCH') {
    return next(action);
  }

  // TODO fetch from live source
  const data = 'foo';
  // store data to cache
  window['__data'] = data;
  return store.dispatch({ type: 'RECEIVE', payload: { data } });
}

export default live;

reducers.js

const mainApp = (state = { }, action) => {
  switch (action.type) {
    case 'FETCH':
    case 'RECEIVE':
      return {
        ...state,
        ...action.payload,
      }
    default:
      return state;
  }
}

export default mainApp