User Guide

206 Chapter 6: Components Dictionary
The second usage example uses a dispatcher/listener event model. A component instance
(
comboBoxInstance) dispatches an event (in this case, scroll) 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” on page 415.
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.
Example
The following example sends a message to the Output panel that indicates the index of the item
that the list scrolled to:
form.scroll = function (eventObj) {
trace("The list had been scrolled to item # " + eventObj.target.vPosition);
}
myCombo.addEventListener("scroll", form);
See also
EventDispatcher.addEventListener()
ComboBox.selectedIndex
Availability
Flash Player 6 (6.0 79.0).
Edition
Flash MX 2004.
Usage
myComboBox.selectedIndex
Description
Property; the index number of the selected item in the drop-down list. The default value is 0.
Assigning this property clears the current selection, selects the indicated item, and displays the
label of that item in the combo box’s text box.
If you assign an out-of-range value to this property, Flash ignores it. Entering text into the text
field of an editable combo box sets
selectedIndex to undefined.
Example
The following code selects the last item in the list:
myComboBox.selectedIndex = myComboBox.length-1;