Tutorial. How to create MIDI synthesizer with MIDI API and Node JS https://medium.com/nebo-15/tutorial-how-to-create-midi-synthesizer-with-midi-api-and-node-js-48d41c162009

midi-api_step8_server.js

const server = app.listen(app.get('PORT'), (error) => {
  if (error) {
    console.log('Server started with an error', error);
    process.exit(1);
  }
  console.log(`Server started and is listening at http://localhost:${app.get('PORT')}`);
});
const socket = new binaryServer({
  server: server,
  path: '/socket',
});