redux-devtools/extension/examples/todomvc/store/configureStore.js

import { createStore } from 'redux';
import rootReducer from '../reducers';
import * as actionCreators from '../actions';

export default function configureStore(preloadedState) {
  const enhancer =
    window.__REDUX_DEVTOOLS_EXTENSION__ &&
    window.__REDUX_DEVTOOLS_EXTENSION__({
      actionCreators,
      serialize: true,
      trace: true,
    });
  if (!enhancer) {
    console.warn(
      'Install Redux DevTools Extension to inspect the app state: ' +
        'https://github.com/zalmoxisus/redux-devtools-extension#installation',
    );
  }

  const store = createStore(rootReducer, preloadedState, enhancer);

  if (module.hot) {
    // Enable Webpack hot module replacement for reducers
    module.hot.accept('../reducers', () => {
      store.replaceReducer(require('../reducers').default);
    });
  }

  return store;
}