But the biggest websites generally don't use 3rd-party JS libraries at all--Google, Yahoo, Facebook, Twitter, etc. all write their own javascript libraries.
Sure there is a long tail of sites that do use jQuery, but most of them don't do very much or get much traffic.
If you look at jQuery's market share by aggregate user sessions or by aggregate time on site across the entire web, it does not look nearly as important.
> Sure there is a long tail of sites that do use jQuery, but most of them don't do very much or get much traffic.
Most sites in general don't get much traffic, but it's absurd to argue that jQuery is not popular amongst large websites. You don't think sites like nytimes.com, craigslist.org, twitter.com (that's right, check the source), live.com, netflix.com and pintrest.com push a lot of traffic? Even more sites use Sizzle, jQuery's selector engine.
YUI stands for Yahoo User Interface. They wrote it and open-sourced it, like Google with the Closure Library. I wouldn't count it as a third-party library.
Right, it's not 3rd party, but it is included in the statistics that show 90% jQuery market share, and the argument was that the biggest websites are not represented there.
Sure there is a long tail of sites that do use jQuery, but most of them don't do very much or get much traffic.
If you look at jQuery's market share by aggregate user sessions or by aggregate time on site across the entire web, it does not look nearly as important.