Question

How do I call a function in ActionScript 3 from JavaScript that has been injected into the page using ExternalInterface.call()?

I’ve tried this a bunch of ways, to no avail.

Here is a simplified version of all the necessary code:

public function myClass() {

    ExternalInterface.addCallback("callASFunction", myASFunction);

    var loadJS:XML =
    <script><![CDATA[

        function(oid){

            ob = document.getElementById(oid);

            if (!window.FB) { /* Include FB JS SDK */ }

            window.fbAsyncInit = function() {

                FB.init({ ... });

                FB.getLoginStatus(function(response) {
                 /* ob.callASFunction(); <= ERROR */
                    ob.callASFunction(response.status); /* <= FIX */
                });
            }
        }

    ]]></script>

    // Inject the JS into the page
    ExternalInterface.call(loadJS, ExternalInterface.objectID);

}

public function myASFunction(vars:String){

    // Do great things

}

Comments

The line marked with <= ERROR throws the following in Chrome:

Uncaught Error: Error calling method on NPObject.

And in FF:

uncaught exception: Error in Actionscript. Use a try/catch block to find error.

I believe that the issue is that the ExternalInterface.addCallback() is not attaching a listener on the Flash object before the ob.callASFunction() is called.

Or, perhaps I’m missing something.

Any pointers would be much appreciated.

Answer 1

There are two possible fixes to this.

Don’t force a parameter for the called AS method

public function myASFunction(vars:String = null){ ... }

or

Always pass a variable to the method

ob.callASFunction(response.status); /* <= FIX */

Bit of a facepalm moment.
:{D

---

Note: I’ve edited my answer to reflect the JS fix, but not the AS one.