Javascript from Flex

Application calls Javascript from Flex

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical">

<mx:Script>
<![CDATA[

/* */
private function initApp():void
{
if(ExternalInterface.available)
{
ExternalInterface.call("alert", "Hello from java script");
}
}
]]>
</mx:Script>
<mx:Button label="Call JS" click="initApp()" />
</mx:Application>