Once again, the jQuery library provides us with a convenient way to take advantage of the Pub/Sub Pattern in our code. Instead of extending its API by adding new methods specifically named "publish" and "subscribe" and introducing new concepts, the developers decided to extend the jQuery.fn.on() and jQuery.fn.trigger() methods with the ability to handle and emit custom events. This way, jQuery can be used to implement a publisher/subscriber communication scheme using the already known convenient methods it provides.
Custom events allow us to use almost any user-defined string value as a common event that we can add listeners for, and also manually fire it on page elements. As an extra but a precious feature, custom events can also carry some extra data to be delivered to the listeners of the event.
The jQuery library added its own custom events implementation, before it was actually added to any web specification. This way, it was proved how...