Read only

• Keyword to prevent a property of a class from being changed

class TicketCreatedListener extends Listener<TicketCreatedEvent> {
  readonly subject = Subjects.TicketCreated;
  queueGroupName = 'payments-service';
  onMessage(data: any, msg: Message) {
    console.log('Event data!', data);
    msg.ack();
  }
}

• readonly only works for properties in CLASSES. Not for conventional variables