<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/03/10/checking-to-see-if-the-externalinterface-api-is-available-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white"
        creationComplete="init();" viewSourceURL="srcview/index.html">

    <mx:Script>
        <![CDATA[
            import mx.controls.Alert;

            private function init():void {
                if (ExternalInterface.available) {
                    ExternalInterface.call("alert",
                            "ExternalInterface is available");
                } else {
                    Alert.show("ExternalInterface is not available");
                }
            }
        ]]>
    </mx:Script>

    <mx:ApplicationControlBar dock="true">
        <mx:Button id="button"
                label="ExternalInterface.available"
                click="init();" />
    </mx:ApplicationControlBar>

</mx:Application>