Beginning ActionScript 2.0

Chapter 10. Interacting with the User

The whole point of using Flash to create web applications is to interact with the user. The richness of the interface depends on having a good selection of events that various components can generate. It's all well if clicking is the only thing that is recognized, but how about mouse-overs, dragging, tabbing, or key presses? These all add to the set of tools for the developer to enhance the user experience.

Most people initially consider only user-generated events such as the ones just mentioned as being important, but there is also the class of system-generated events that occur as a result of either data changes or network communications. You may have asked the server for new data, or perhaps a value changed in response to a user interaction, and that new value needs to be broadcasted to other components. Though you may wonder how this falls under "interacting with the user," keep in mind that the data generally feeds what the user sees in some way or another. Changes to background data often require updating elements of the user interface.

Handling Events

Any time an event is generated, you need a way to act on that event. When a button is clicked, specific code needs to run. When an entry is selected in a drop-down menu, you need to know that a change has happened, and you need to find out which element is chosen. The code that you write to respond to an event is called an event handler. Event handlers keep you from having to manually query ...