To build interactive web applications, we need to observe the user's activities and respond to them. We have seen that jQuery's event system can make this task easy, and in the chapters so far we have used this event system many times.
In Chapter 3, Handling Events, we touched upon a number of features that jQuery provides for reacting to events. In this more advanced chapter, we will cover:
Event delegation, and the challenges it presents
Performance pitfalls associated with certain events, and how to address them
Custom events that we define ourselves
The special event system that jQuery uses internally for sophisticated interactions