Javascript – Problem accessing ExternalInterface exposed method in Google Chrome

externalinterfaceflashgoogle-chromejavascript

My simple ActionScript
I am trying to use Flash's ExternalInterface to setup a callback so that JavaScript can call a method on my Flash object. Everything works fine in Safari, Firefox and in IE, but I cannot get Chrome working. When I try the code on Chrome, I get the following error:

Uncaught TypeError: Object #<an
HTMLObjectElement> has no method
'setText'

Here is the example HTML I am using (again, works fine in Safari, FF and IE)

<html><body>
<div id="mycontent"></div>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/swfobject/2.2/swfobject.js"></script>
<script type="text/javascript">
swfobject.embedSWF("http://invincible.dynalias.com:8080/HelloWorld.swf", "mycontent", "400", "420", "9.0.0","expressInstall.swf", {}, {allowScriptAccess:'always'},{id:'hw',name:'hw'});

function getFlash(movieName) {
   return ( navigator.appName.indexOf("Microsoft") != -1) ? window[movieName] : document.getElementById(movieName);
}
</script><p>
  <input type="text" id="exampleText" /> <input type="button" value="Set Text" onclick="getFlash('hw').setText(document.getElementById('exampleText')
.value)" />
</body>
</html>

and here is the ActionScript…

package {
  import flash.display.Sprite;
  import flash.text.TextField;
  import flash.external.ExternalInterface;
  import flash.system.Security;

  public class HelloWorld extends Sprite {

    private var textField:TextField = new TextField();
    public function HelloWorld() {
      Security.allowDomain("*");
      ExternalInterface.addCallback("setText", this.setText);
      textField.text = "Hello, world!";
      addChild(textField);
    }   
    public function setText(text:String):void {
      this.textField.text = text;
    }   
  }
}

Best Answer

I agree with Robson that it is a race condition, but it's not in 'writing the Flash tag' and adding a timer is not a good solution - in fact its very dangerous.

The problem is that the SWF itself isn't loaded and had a chance to initialize your external interface. For a small SWF in Chrome the timing may be more sensitive than other browers, but the underlying problem isn't specific to Chrome.

What you need to do is this :

In Actionscript

Call this function from your constructor :

public function InitializeExternalInterface():void 
{   
      if (ExternalInterface.available) {

           // register actionscript functions so they can be called by JS   
           ExternalInterface.addCallback("activate", activate);
           Security.allowDomain("www.example.com");     

           // send message to parent page that SWF is loaded and interface active
           trace("External Interface Initialized...");
           ExternalInterface.call("flashInitialized")
      }
      else 
      {
          trace("ERROR: External Interface COULD NOT BE Initialized...");
      } 
}

In your HTML

 <script>

     function flashInitialized() 
     {
         alert("Initialized!");      // remove this obviously!
         $('#Main')[0].activate();   // safe to call Flash now
     }

 </script>

You may find on your local machine that it works without this, but as soon as you add network delays into the equation you'll regret not doing this. An arbitrary timer is a bad idea because you will still get the error on a slow connection. This method lets the page call the flash object at the earliest possible time.

Note: Using jQuery's 'on ready' pattern is NOT a solution to the problem - although at first I mistook it for one.

$(function() 
{
   $('#animation')[0].SetTitle("Hello"); 
}

Also swfobject's callbackFn is also not a solution becasue that just tells you when the tag is inserted and not when the SWF is loaded.

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