Why is Silverlight 1 broken with Firefox 3 and how do I fix it?

re: Why is Silverlight 1 broken with Firefox 3 and how do I fix it?

Robert O'Callahan — Wed, 18 Jun 2008 01:12:11 GMT

It's a race condition in Microsoft's Silverlight detection script, not Firefox. <object> loading has always been defined to be asynchronous so you shouldn't rely on methods like IsVersionSupported returning valid data when you call them immediately after starting the load.

re: Why is Silverlight 1 broken with Firefox 3 and how do I fix it?

nparker — Wed, 18 Jun 2008 01:37:18 GMT

Thanks Robert, I have updated the post now.

re: Why is Silverlight 1 broken with Firefox 3 and how do I fix it?

Robert O'Callahan — Wed, 18 Jun 2008 05:31:48 GMT

Thanks Nigel.

BTW the behaviour change in Firefox occurred right at the start of the Gecko 1.9 development cycle --- in late 2005! So it's surprising, and unfortunate, that this wasn't noticed in time to fix the detection script before it was rolled out.

re: Why is Silverlight 1 broken with Firefox 3 and how do I fix it?

nparker — Wed, 18 Jun 2008 06:25:12 GMT

I understand that things have worked this way since Sep-2005 but that said if you run the following javascript in FireFox 2 it returns true 100% of the time when Silverlight is installed.

var a = document.getElementById('a');

a.innerHTML='<object type="application/x-silverlight" data="data:," />';

var b=a.childNodes[0];

alert(b.IsVersionSupported('1.0'));

</script>

Run it in FireFox 3 and it generates an error "b.IsVersionSupported is not a function".

re: Why is Silverlight 1 broken with Firefox 3 and how do I fix it?

someone — Thu, 19 Jun 2008 15:34:34 GMT

Wait a minute, is this a client-side JS file or server-side? What do USERS (not developers) have to do to make it work with FF3.0?

re: Why is Silverlight 1 broken with Firefox 3 and how do I fix it?

nparker — Fri, 20 Jun 2008 02:02:13 GMT

@someone

Although this is client-side JS it is up to the site owner to fix the .js file that is downloaded to the client. Users are unable to make these changes themselves to make Silverlight 1 sites work with FF3.

I have sent off some internal emails to site owners of various large content sites (including microsoft.com, nba.com and mlb.com) but it will be up to them to make changes.

In the meantime I recommend contacting the site owner of the site that is not working and continue to view those sites in FF2 until they are updated.

An example of a site that works with Silverlight 1 and Firefox 3 is

http://autotrader.co.nz/UsedItemDetails.aspx?Ne=220&N=221&item=124886&sid=11AA59BE121A click "Play Movie" below the image.