React Redux state is lost at page refresh

Question

in my react app I have 3 components. from the 1st component by a button, I use Link to go to the 2nd component. at the 2nd I create a state (redux store), manipulate it and when manipulation is finished by submitting button I redirect to the 3rd component. at the 3rd component, I also see the state (by redux chrome tool) but here when I refresh the page (the webpack thing when a code is changed and saved), I lose the sate and get an empty Object.

this is the structure of my app.

index.js

const store = createStore(
  rootReducer,
  composeWithDevTools(applyMiddleware(thunk))
);

ReactDOM.render(
  <BrowserRouter>
    <Provider store={store}>
      <Route component={App} />
    </Provider>
  </BrowserRouter>,
  document.getElementById("root")
);

App.js

const App = ({ location }) => (
  <Container>
    <Route location={location} path="/" exact component={HomePage} />
    <Route location={location} path="/GameInit" exact component={GameInit} />
    <Route location={location} path="/Battle" exact component={Battle} />
  </Container>
);

App.propTypes = {
  location: PropTypes.shape({
    pathname: PropTypes.string.isRequired
  }).isRequired
};

export default App;

Here at HomePage, I have a button that links to GameInit

const HomePage = () => (<Button color="blue" as={Link} to="/GameInit">START GAME</Button>);
export default HomePage;

and the GameInit Page looks like

class GameInit extends Component {
  componentWillMount() {
    const { createNewPlayer} = this.props;
    createNewPlayer();
  }
/* state manipulation till it gets valid */
 palyerIsReady()=>{ history.push("/Battle");}

export default connect(mapStateToProps,{ createNewPlayer})(GameInit);

and finally Battle component where I first see the state but lose on refresh

class Battle extends Component {
  render() {return (/*some stuff*/);}}

Battle.propTypes = {
  players: PropTypes.object.isRequired // eslint-disable-line
};
const mapStateToProps = state => ({
  players: state.players
});
export default connect(mapStateToProps,null)(Battle);

Answer 1

You can easily persist it in the localstorage. Check the example below.

const loadState = () => {
  try {
    const serializedState = localStorage.getItem('state');
    if(serializedState === null) {
      return undefined;
    }
    return JSON.parse(serializedState);
  } catch (e) {
    return undefined;
  }
};

const saveState = (state) => {
  try {
    const serializedState = JSON.stringify(state);
    localStorage.setItem('state', serializedState);
  } catch (e) {
    // Ignore write errors;
  }
};

const peristedState = loadState();

store.subscribe(() => {
  saveState(store.getState());
});

const store = createStore(
  persistedState,
  // Others reducers...
);

render(
  <Provider store={store}>
    <App/>
  </Provider>,
  document.getElementById('root');
);

---

Serialization is an expensive operation. You should use a throttle function (like the one implemented by lodash) to limit the number of saves.

Eg:

import throttle from 'lodash/throttle';

store.subscribe(throttle(() => {
  saveState(store.getState());
}, 1000));