index.js

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './components/app/App';
import registerServiceWorker from './registerServiceWorker';
import {BrowserRouter} from 'react-router-dom';
import {createStore} from 'redux';
import {Provider} from 'react-redux';
import reducer from './reducers/index'

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

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

const store = createStore(reducer, loadState());
store.subscribe(() => {
	saveState({
		todos: store.getState().todos
	});
});
ReactDOM.render(
	<Provider store={store}>
		<BrowserRouter>
			<App/>
		</BrowserRouter>
	</Provider>,
	document.getElementById('root'));
registerServiceWorker();