server.ts

import * as http from 'http';
import app from './backend/app.js';
import logger from './backend/logger.js';

// Normalize a port.
function normalizePort(val: string): string | number | boolean {
  const port = parseInt(val, 10);

  if (Number.isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
  }

  return false;
}

// Get port from environment and store in Express.
const port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

// Create HTTP server.
const server = http.createServer(app);

// Event listener for HTTP server "error" event
function onError(error: NodeJS.ErrnoException) {
  if (error.syscall !== 'listen') {
    throw error;
  }

  const bind = typeof port === 'string' ? `Pipe ${port}` : `Port ${port.toString()}`;

  switch (error.code) {
    case 'EACCES':
      logger.error(`${bind} requires elevated privileges`);
      process.exit(1);
      break;
    case 'EADDRINUSE':
      logger.error(`${bind} is already in use`);
      process.exit(1);
      break;
    default:
      throw error;
  }
}

// Event listener for HTTP server "listening" event.
function onListening() {
  const addr = server.address();
  let bind = '';
  if (addr) {
    bind = typeof addr === 'string' ? `pipe ${addr}` : `port ${addr.port}`;
  }
  logger.info(`Server is listening on ${bind}`);
}

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);