The way how events are raised and how listeners are attached on the events is a part of a core in many modern applications. It plays an important role in some enterprise design patterns (MVC, for example).

He starts with the basics of event handling - some of the terms and descriptions of basic functionality that any good event handler would have. He describes the most common setup of an event-interaction relationship. Then, it's on to the code, showing first three different ways to call functions (by name, by variable, and by callback).

He finishes it off with a functional example that responds to a a call to fireEvent (five times) and handles each by calling the function in the callback information (myFunction).