I'm looking to implement adblock support (via adblockplus's format) to Uzbl and it would be nice to have a 'reason' for why a request is being made. As an example, the format supports only blocking requests based on the fact that it's a stylesheet, a script, image, XMLHttpRequest, etc. Documentation for the format is here[1]. [1]https://adblockplus.org/en/filters#options
Is the idea that XMLHttpRequest can never be used to retrieve an image or a script? That would be obviously incorrect.
That's probably one use. I think it's mainly used to try and consolidate rules together. A directory might contain CSS that is clean, but the JS is unwanted, so the rule has '~stylesheet' as an option. There are *lots* of rules (I have 42k from easylist), so collapsing rules differing by a '*.js' and '*.html' is useful. I have seen sites load URIs such as "data:image/jpeg;base64goop" presumably to get around adblockers.
Looking down in WebCore itself, this data isn't exposed AFAICS. I'll open a separate bug for it.