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 execute 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 following discussion expects you to understand objects, which are covered in Chapter 12.
