logger.js

const logger = state => {
  return next => {
    return action => {
      console.log("Previous state:");
      console.log(state.getState());
      console.log("Dispatching action:");
      console.log(action);
      const result = next(action);
      console.log("Next state:");
      console.log(state.getState());
      return result;
    };
  };
};