Server side render with React and Express

expressServer.js

app.get("*", (req, res, next)=>{
  ServerSideRenderer.render(req)
    .then((results)=>{
      if (results.redirect)
        res.redirect(302, results.redirect);
      else if (results.html) {
        res.status(200).render('index', {react: results.html});
      } else next();
    }, next);
});

ServerSideRenderer.js

var React    = require('react');
var ReactDom = require('react-dom/server');
import {match, RouterContext} from "react-router";
import Main from "../../app/Main";
import routes from "../../app/routes";

export default class ServerSideRenderer {

  static render(req) {
    return new Promise((resolve, reject)=> {
      match({routes: routes(), location: req.url}, (error, redirectLocation, renderProps)=> {
        if (error) {
          reject(error);
        } else if (redirectLocation) {
          resolve(REDIRECT(redirectLocation.pathname + redirectLocation.search))
        } else if (renderProps) {
          resolve(HTML(
            ReactDom.renderToString(
              <Main children={renderProps.children}>
                <RouterContext {...renderProps}/>
              </Main>
            )
          ));
        } else {
          reject();
        }
      });
    })
  }
}

const REDIRECT = (redirect) => ({redirect});
const HTML     = (html) => ({html});