app.js
function onError(error) {
    if (error.syscall !== 'listen') throw error;

    const bind = (typeof port === 'string')
                ? 'Pipe ' + port
                : 'Port ' + port;

    // handle specific listen errors with friendly messages
    switch (error.code) {
      case 'EACCES':
        console.error(bind + ' requires elevated privileges');
        process.exit(1);
        break;

      case 'EADDRINUSE':
        console.error(bind + ' is already in use');
        process.exit(1);
        break;

      default:
        throw error;
    }
  }
function onError(error) {
    if (error.syscall !== 'listen') throw error;

    const bind = (typeof port === 'string')
                ? 'Pipe ' + port
                : 'Port ' + port;

    // handle specific listen errors with friendly messages
    switch (error.code) {
      case 'EACCES':
        console.error(bind + ' requires elevated privileges');
        process.exit(1);
        break;

      case 'EADDRINUSE':
        console.error(bind + ' is already in use');
        process.exit(1);
        break;

      default:
        throw error;
    }
  }
function onError ( error ) { if ( error . syscall !== 'listen' ) throw error ; const bind = ( typeof port === 'string' ) ? 'Pipe ' + port : 'Port ' + port ; // handle specific listen errors with friendly messages switch ( error . code ) { case 'EACCES' : console . error ( bind + ' requires elevated privileges' ) ; process . exit ( 1 ) ; break ; case 'EADDRINUSE' : console . error ( bind + ' is already in use' ) ; process . exit ( 1 ) ; break ; default : throw error ; } }
Event listener for HTTP server "error" event.
Event listener for HTTP server error event .