Back in the 90's there existed the phenomenon of C programmers who didn't really understand pointers. You'd try and tease that out in an interview, but the best way to find someone who really understood C was to find somebody with experience in Assembly Language.
When we're hiring for Javascript positions, we don't really care if they have experience in the framework-du-jour. Heck, we don't really care if they have Javascript experience, we just want to make sure they can learn it and write it in an idiomatic fashion. Can they think in a functional, asynchronous fashion?
Today the equivalent for Javascript is probably a Lisp. Lisp experience is probably a better predictor of a good Javascript programmer than Javascript experience is.
Question 1: Is this recognized by other employers? If I tell a kid that learning Clojure will make their resume stand out much better and be useful for much longer than learning the framework-du-jour will, am I steering them wrong?
Question 2: Are there any other actionable similar recommendations? Winning a programming contest is also a good predictor, but it's only available to the few.
Also keep in mind that there is a industry full of recruiters who don't agree! If the job ad says you need previous experience with Boongolatr.js version 3.147 then Boongolatr.js version 3.147 it is. Then good fundamentals and knowing Scheme, Haskell and shit won't help you.