Dynamic Event Handling
Manage event listeners dynamically by using one-time listeners, removing or counting listeners, and adjusting listener limits for efficient, safe event-driven applications.
In real-world applications, events and their listeners often need to change dynamically. For instance:
Some listeners should only react to an event once.
Specific listeners might need to be removed based on conditions.
We may need to debug or track the number of active listeners.
Listener limits might need to be increased or removed for flexibility.
In this lesson, we’ll explore these dynamic features of the EventEmitter class with practical examples, continuing with the context of a chatroom application.
Using one-time listeners
The .once() method registers a listener that executes only the first time an event is emitted. After that, it’s automatically removed.
Let’s add a one-time listener to display a welcome message the first time a user joins the chat.