const promisifyEvent = require('promisify-event');

// Promisify server's `listening` event:
promisifyEvent(server, `listening`).then(() => {
  // ...
});

// Promisify `error` event. `error` event always rejects the promise:
promisifyEvent(server, 'error').catch(() => {
  // ...
});

// Cancel event subscription and promise (it will be never fulfilled):
var listeningPromise = promisifyEvent(server, `listening`);

listeningPromise.cancel();

listeningPromise.then(() => {
  // Will never happen
});