ActionScript for Flash MX: The Definitive Guide, Second Edition

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Chapter 10: Events and Event Handling

• SharedObject

• Sound

• Stage

• TextField

• XML

• XMLSocket

For details on the specific events supported by these objects, see each object’s entry

in the Language Reference.

Event Handling

Not every event triggers the execution of code or affects a movie. For example, a user

can generate dozens of events by clicking repeatedly on a button, but those clicks

may be ignored. Why? Because, on their own, events can’t cause code to execute—

we must write code to react to events explicitly. To instruct the interpreter to exe-

cute some code in response to an event, we create either an event handler or an event

listener that describes the action to take when the specified event occurs.

Due to its unusual evolution, ActionScript has four different ways of handling events:

• Event handler properties

• Event listeners

• Button event handlers with the syntax:

on (eventName) {

statements

}

• Movie clip event handlers with the syntax:

onClipEvent (eventName) {

statements

}

Let’s take a look at these event-handling mechanisms individually. Much of the fol-

lowing discussion expects you to understand objects, which are covered in

Chapter 12.

Event Handler Properties

Event handlers are so named because they catch,orhandle, the events in a movie. An

event handler is simply