storage-middleware.js

function timestampAction(action) {
  return {
    action,
    time: Date.now()
  }
}

function storageMiddleware() {
  return () => next => action {
    const stampedAction = timestampAction(action);
    
    localStorage.setItem('STORAGE-KEY', JSON.stringify(stampedAction));
    
    next(action);
  }
}