React router matching

app.js

// Server Side Rendering based on routes matched by React-router.
app.use((req, res) => {
    match({
        routes,
        location: req.url
    }, (err, redirectLocation, renderProps) => {
        if (err) {
            return res.status(500).end('Internal server error');
        }

        if (!renderProps) {
            return res.status(404).end('Not found!');
        }

        const initialState = {
            posts: [],
            post: {}
        };

        const store = configureStore(initialState);

        fetchComponentData(store.dispatch, renderProps.components, renderProps.params).then(() => {
            const initialView = renderToString(
                <Provider store = {store} >
                  <RouterContext {...renderProps}/>
                </Provider>
            );

            const finalState = store.getState();

            res.status(200).end(renderFullPage(initialView, finalState));
        }).catch(() => {
            res.end(renderFullPage('Error', {}));
        });
    });
});