I like Firefox extensions and use a few myself. Web development without Web Developer toolbar and LiveHTTPHeaders extension would be pretty gruesome. However, there’s a downside to their use that is slowly starting to bother me.

They often influence the way Javascript on page gets executed and can produce weird errors.

I first noticed this while using Web Developer toolbar. Every now and then I got a strange exception, but I didn’t worry too much. After all, it wasn’t really surprising coming from an extension that by its very nature dabbled with the way browser interprets and displays a page and it didn’t really stop the script from working. Not pretty, but you learn to live with it.

Comes this weekend and I get a report that file upload doesn’t work in latest Firefox. I suspected extension conflicts and further examination proved the point. Page worked just fine in the same environment sans extensions.

So what can you do, when you stumble on a problem like that?

Testing your site in various browsers can be troublesome enough. Testing all combinations of extensions even for one browser would simply be impossible. You can’t exactly expect your users to uninstall their extensions just for you, but making workarounds for them doesn’t seem feasible either.

So far I don’t see a good solution. Any ideas?