Question

So I have an Application Sandbox HTMLLoader object which I create in AIR and simply want to call ActionScript methods from JavaScript. In Flash, this is accomplished through our trusty ExternalInterface.addCallback() function. However in AIR, things are quite a bit different, and I just can’t seem to get it to work.

Here is a simplified overview of my project:

My AIR (ActionScript) main:

public class Main extends Sprite {      public var _as3Var:String = 'testing';     public function as3Function():void     {         trace('as3Function called from Javascript');     }      public function Main() {         NativeApplication.nativeApplication.addEventListener(InvokeEvent.INVOKE, onInvoke);     }      protected function onInvoke(e:InvokeEvent):void {         NativeApplication.nativeApplication.removeEventListener(InvokeEvent.INVOKE, onInvoke );         var app = new App();         addChild(app);         app.init(new ExternalContainer(), e.currentDirectory, e.arguments);     } } 

And this is how I create my HTMLLoader object:

{     _html = new HTMLLoader();     _html.useCache = false;     _html.runtimeApplicationDomain = ApplicationDomain.currentDomain;     _html.load(new URLRequest('sandbox/AirRoot.html'));     _html.width = 800;     _html.height = 600;     App.ref.addChild(_html); } 

And at last, here is my snippet of JavaScript in my AirRoot.html file which is trying to call the public method as3Function() declared in my Main class:

Exposed.testAs3 = function() {     air.trace('Exposed.testAs3 called');            /* This works fine. */     air.trace('runtimeVersion:');                   /* This works fine. */     air.trace(air.NativeApplication.nativeApplication.runtimeVersion);  /* This works fine. */     air.trace('seeing if I can get to AS3 params...');  /* This works fine. */      /* This doesn't work - get the following error: TypeError: Value undefined does not allow function calls. */     air.NativeApplication.nativeApplication.as3Function(); } 

What am I missing?

Answer 1

OK, I am going to answer my own question. I promise this was not a ploy to gain more reputation points, but I was seriously confused today but have now found the appropriate answers and documentation – which is usually the main problem to many an engineer’s question…

Anyway, the answer:

The AIR HTMLLoader object contains a magical property, HTMLLoader.window, which is a proxy to the JavaScript window object. So setting HTMLLoader.window = AS3Function; is one way – or in relation to my previously included example (assuming I setup a static property called Main which pointed to the Main class):

_html.window.as3Function = Main.as3Function; 

And now in JavaScript I can just call as3Function as:

<script>     window.as3Function(); </script> 

Another interesting property is the JavaScript ‘window.htmlLoader’ object. It is a proxy to the AS3 HTMLLoader parent object, in my case, the _html object. From this you can access things in relation to the _html object from JavaScript.