ActionScript 2.0 Components Language Reference 
ActionScript 2.0 Components Language Reference |
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Flash Player 6 (6.0.79.0).
Flash MX 2004.
Usage 1:
var listenerObject:Object= new Object();listenerObject.change = function(eventObject:Object) {// Your code here. };listInstance.addEventListener("change",listenerObject);
Usage 2:
on (change) {
// Your code here.
}
Event; broadcast to all registered listeners when the selected index of the list changes as a result of user interaction.
The first usage example uses a dispatcher/listener event model. A component instance (listInstance) dispatches an event (in this case, change) and the event is handled by a function, also called a handler, on a listener object (listenerObject) that you create. You define a method with the same name as the event on the listener object; the method is called when the event is triggered. When the event is triggered, it automatically passes an event object (eventObject) to the listener object method. Each event object has properties that contain information about the event. You can use these properties to write code that handles the event. For more information, see EventDispatcher class (API).
Finally, you call the addEventListener() method on the component instance that broadcasts the event to register the listener with the instance. When the instance dispatches the event, the listener is called.
The second usage example uses an on() handler and must be attached directly to a List instance. The keyword this, used inside an on() handler attached to a component, refers to the component instance. For example, the following code, attached to the List instance my_list, sends "_level0.my_list" to the Output panel:
on (change) {
trace(this);
}
The following example adds three items to the List component. Changing the selected value of the list causes the value of the newly selected item to be displayed in the Output panel. To try this code, drag a List component to the Stage and give it the instance name my_list. Add the following code to Frame 1 in the timeline:
var my_list:mx.controls.List;
my_list.addItem({data:'flash', label:'Flash'});
my_list.addItem({data:'dreamweaver', label:'Dreamweaver'});
my_list.addItem({data:'coldfusion', label:'ColdFusion'});
// Create listener object.
var listListener:Object = new Object();
listListener.change = function(evt_obj:Object) {
trace("Value changed to: " + evt_obj.target.value);
}
// Add listener.
my_list.addEventListener("change", listListener);
EventDispatcher.addEventListener()
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