server.js

const express = require( 'express' );
const next    = require( 'next' );

// Import middleware.
const routes = require( './routes' );

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

app.prepare()
	.then( () => {

		// Create server.
		const server = express();

		// Use our handler for requests.
		server.use( handler );

		// Don't remove. Important for the server to work. Default route.
		server.get( '*', ( req, res ) => {
			return handle( req, res );
		} );

		// Get current port.
		const port = process.env.PORT || 8080;

		// Error check.
		server.listen( port, err => {
			if ( err ) {
				throw err;
			}

			// Where we starting, yo!
			console.log( `> Ready on port ${port}...` );
		} );
	} );