next.js

/* eslint-disable no-param-reassign */
const next = require('next');

const dev = process.env.NODE_ENV !== 'production';
const app = next({ dev, dir: './app' });
const handle = app.getRequestHandler();

module.exports = (async server => {
  await app.prepare();
  // Middleware to insert app and handle inside the req object.
  server.use('/', (req, res, n) => {
    req.app = app;
    req.handle = handle;
    n();
  });
  server.originalListen = server.listen;
  server.listen = (port) => {
    // If none of the custom routing handlers from express are hit,
    // defer to next's own handler.
    server.get('*', (req, res) => {
      req.handle(req, res);
    });
    server.originalListen(port);
  };
  return server;
});