使用JS或PHP在Firefox中启用检测扩展

Question

Is there anyway that we can find out the extensions that are enabled and disabled in firefox using Javascript or PHP script?

I need to alert a message if the extension is enabled.

Thanks in advance.

Answer 1

This depends on the extension.

Some extensions actually modify the html/dom of your page so you can easily identify them.

like InFormEnter: This extension creates img elements which you can identify using jquery:

if ($("img.ife_marker").length > 0) alert("InformEnter installed!");

But only a few do this, and you can only guess the behaviour (or fork the extension to add something like this).

IF you have an extension that has such a behaviour (you can create a test-page and use firebug to search the dom tree for added/changed elements) then you could write some javascript (like the example above) and use JSON to send the information back to your server.

Some extensions might react to requests you send out (like modify headers) - then you can create an ajax request with a know header and check this.

The only reason I could theoretically think of when this makes any sense would be in a closed office environment where you want to check for specific addons that have to be installed in order for your app to work. In that case I would actually create a fork of the extension and make it append such a marker to the page.

Edit: since you mention yslow: No yslow does not do ANYTHING to the page. It actually only takes information already available within firefox and analyzes the page based on that. It does not even create any extra http requests which you could theoretically pick up on.