Events drive applications. Nearly everything that happens in an ActionScript 3.0 application is triggered by events. There are two basic types of events: user and system. When a user clicks a button or types on the keyboard events are fired. These are examples of user events.System events are those which occur because of something based on time or asynchronous operations. For example, loading an external resource might trigger a load complete or a load error event. In this chapter, we'll look at what events are, what design problems they solve, how they related to known design patterns, and how they are used in ActionScript 3.0. |