Ask HN: Is it bad to master jQuery without any knowledge of the undelying JS?

Might not call it bad, but you should really also learn JS - as brilliant as jQuery is, it can't really do everything. It's also much better to know js in order to debug stuff that misbehave (you can also download the un-minified jQuery code and just step into to it ... can save a few hairs off your head)

As others have mentioned, it's impossible to "master" jQuery without a very solid understanding of JavaScript. You'll end up with code that does way more work than it needs to, and is way sloppier than it should be. I'm pretty certain that mastery is impossible without an understanding of the foundation and the abstractions.