vanillajs plain js lol. But jquery is also originally intended as a polyfill! there are many cases where jquery is unnecessary but there might be just a little too much negativity about it.
For the most part though, in today's standard of updates and etc, it really shouldn't be a big deal to work with mostly vanilla js and worrying about dead browsers. stupid IE >:[
Sent in a PR to HTMLy to use alot less of the jqueryUI library. The only thing left is tag auto completion which is nice but gotta somehow get around that. At the very least, I was able to slim the lib down to just what is needed instead of the whole fat library.