index.js

import React from 'react';
import ReactDOM from 'react-dom';
import { createStore, combineReducers, applyMiddleware, compose } from 'redux';
import thunk from 'redux-thunk';
import { Provider } from 'react-redux';
import burgerBuilderReducer from './store/reducers/burgerBuilder';
import orderReducer from './store/reducers/order';
import authReducer from './store/reducers/auth';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';
import { BrowserRouter } from 'react-router-dom';

const rootReducer = combineReducers({
  burgerBuilder: burgerBuilderReducer,
  order: orderReducer,
  auth: authReducer
});

const composeEnhancers = process.env.NODE_ENV === 'development' ? window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ : null || compose;

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

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

// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: http://bit.ly/CRA-PWA
serviceWorker.unregister();