Create-React-App loses Redux store state on hot reload

Question

I've created an app with Create-React-App and hot reloading is working, however the Redux state is lost. If I edit any component, e.g. to change a title, the state is lost - most annoying is that the user is logged out because the token stored in the state is lost. I've followed various examples including (https://redux.js.org/recipes/configuring-your-store) and can't figure out what's wrong here.

Any ideas what I've missed? Thank you!

index.js

const renderApp = () => {
    ReactDOM.render(
        <App />, document.getElementById('root')
    );
};

if (process.env.NODE_ENV !== 'production' && module.hot) {
    module.hot.accept('./App', renderApp);
}

renderApp();

store.js

const inititalState = {};

const store = createStore(
    rootReducer, 
    inititalState, 
    compose(applyMiddleware(thunk), 
        window.__REDUX_DEVTOOLS_EXTENSION__&& window.__REDUX_DEVTOOLS_EXTENSION__()));

if (process.env.NODE_ENV !== 'production' && module.hot) {
    module.hot.accept('./reducers', () => store.replaceReducer(rootReducer));
}

export default store;

reducers/index.js

import { combineReducers } from 'redux';
import errorReducer from './errorReducer';
import authReducer from './authReducer';

export default combineReducers({
    'errors': errorReducer,
    'auth': authReducer,
});

App.js:

class App extends Component {
    render() {
        return (
            <Provider store = { store }>
                <Router>
                    <div>
                        <Navbar />
                        <Route exact path="/" component={ Home } />
                        <div className="container">
                            <Route exact path="/register" component={ Register } />
                            <Route exact path="/login" component={ Login } />
                            <Route exact path="/forgotpassword" component={ ForgotPassword } />
                        </div>
                    </div>
                </Router>
            </Provider>
        );
    }
}

export default App;

From package.json:

  "dependencies": {
    "bootstrap": "^4.2.1",
    "classnames": "^2.2.6",
    "jquery": "^3.3.1",
    "jwt-decode": "^2.2.0",
    "react": "^16.7.0",
    "react-dom": "^16.7.0",
    "react-redux": "^6.0.0",
    "react-router-dom": "^4.3.1",
    "react-scripts": "2.1.2",
    "reactstrap": "^7.0.2",
    "redux": "^4.0.1",
    "redux-thunk": "^2.3.0",
    "updeep": "^1.1.0"
  },

Answer 1

If you only need to save the token you could use the localstorage, if you want to save a lot of data you should take a look at redux-persist.

Example on saving using localStorage:

localStorage.setItem(token, res.data.token);

Example on retrieving using localStorage:

localStorage.getItem(token);

Example on removing the token if the user logs out:

localStorage.removeItem(token);