Here is my code:

store.js

import {createStore, applyMiddleware, compose} from 'redux';
import {fromJS} from 'immutable';
import {routerMiddleware} from 'react-router-redux';
import createSagaMiddleware from 'redux-saga';
import createReducer from './reducers';

const sagaMiddleware = createSagaMiddleware();

export default function configureStore(initialState = {}, history) {
    // Create the store with two middlewares
    // 1. sagaMiddleware: Makes redux-sagas work
    // 2. routerMiddleware: Syncs the location/URL path to the state
    const middlewares = [sagaMiddleware, routerMiddleware(history)];

    const enhancers = [applyMiddleware(...middlewares)];

    const store = createStore(createReducer, fromJS(initialState), enhancers);

    // Extensions
    store.runSaga = sagaMiddleware.run;
    store.asyncReducers = {}; // Async reducer registry

    return store;
}

Routes.js

import React from 'react';
import {Route, Router, IndexRoute, browserHistory} from 'react-router';
import {syncHistoryWithStore} from 'react-router-redux';
import store from './store';

import Welcome from './containers/Welcome';

const history = syncHistoryWithStore(browserHistory, store);

const routes = (
    <Router history={history}>
        <Route path="/">
              <IndexRoute component={Welcome} />
        </Route>
    </Router>
);

export default routes;

Index.js

import React from 'react';
import ReactDOM from 'react-dom';
import {browserHistory} from 'react-router';
import { Providers } from 'react-redux';
import configureStore from './store';
import routes from './routes';


const initialState = {};
const store = configureStore(initialState, browserHistory);

ReactDOM.render(
    <Provider store={store}>
        {routes}
    </Provider>, document.getElementById('main-content')
);

I can't find where the culprit is. I tried to debug it, but can't found what really make it those error. error: Uncaught TypeError: store.getState is not a function

Any solution?