How can I discover that the connection with Mongo was reestablished?

I need emit an event when the connection was connected and disconnected. My problem is to detect when the connection was reestablished.

The mongo drive emit um event when the connection was disconnected (on error), but it doesn't emit a event when the connection is reestablished.

MongoClient.connect(mongoUrl, function (err, db) {
  if (err) {
    console.log('Error on connecting to mongo!');
    console.error(err);

    reconnect();

    return;
  }

  console.log('Mongo connected!');
  emit('connected', db);   // This event is emitted only on the first connection.

  db.on('error', function (err) {
    console.log('Mongo connection broken!');
    console.error(err);
    emit('disconnected');
  });
}

Analyzing the code I discovered the serverConfig object.

db.serverConfig.on('reconnect', function() {
  console.log('DB reconnected');
});

Is it a good practice to use this internal object?

Thanks.