<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" width="400" height="300">
 
    <mx:Script>
        <![CDATA[
            import mx.controls.Alert;
 
            protected function callJavaScript():void {
                if (tree.selectedItem) {
                    var str:String = tree.selectedItem.@label;
                    ExternalInterface.call("alert", str);
                } else {
                    Alert.show("You dont have anything selected");
                }
            }
        ]]>
    </mx:Script>
 
    <mx:Tree id="tree" labelField="@label" width="200">
        <mx:dataProvider>
            <mx:XML xmlns="">
                <root label="Root">
                    <node label="1. One" />
                    <node label="2. Two">
                        <node label="2a. Two" />
                        <node label="2b. Two" />
                        <node label="2c. Two" />
                        <node label="2d. Two" />
                    </node>
                    <node label="3. Three" />
                    <node label="4. Four" />
                    <node label="5. Five" />
                    <node label="6. Six" />
                    <node label="7. Seven" />
                    <node label="8. Eight" />
                    <node label="9. Nine" />
                </root>
            </mx:XML>
        </mx:dataProvider>
    </mx:Tree>
    <mx:Button label="Send Tree selected item to JavaScript" click="callJavaScript();" />
 
</mx:Application>