redux-logger-immutable.js

import { createLogger } from 'redux-logger';

const logger = createLogger({
  stateTransformer: (state) => {
    const newState = {};
    const stateObj = state.toObject();

    for (const i of Object.keys(stateObj)) {
      if (Iterable.isIterable(stateObj[i])) {
        newState[i] = stateObj[i].toJS();
      } else {
        newState[i] = stateObj[i];
      }
    }

    return newState;
  }
});

const store = createStore(
  reducer,
  Immutable.fromJS(preloadedState),
  applyMiddleware(logger)
);