[purpleturtle]

builtwith doesn't show all js libs. it just whitelists the top 20 i believe. looks like Wapanalyzer might be similar.

alexa is also unrelated to broad js penetration detection.

not sure how ghostery is relevant.

the novelty of libscore is that it detects all js libs (even brand new ones with only 20 sites using it); doesn't use a dumb whitelist filter.

[AdamTReineke]

Great example is to look at Microsoft.com and see a bunch of tiny "MS" prefixed libraries that probably only exist on their web properties.