I have 0 years hiring people, my experience is this. The language(s) you write code in don't mean a thing. It's the ecosystem. I'm a JS programmer, but that is not why you should hire me, it's my experience with the DOM, HTTP, indexeddb, File API, documentFragment, Fetch API, TreeWalker, NPM, WebGL, interactive SVG, the pros and cons of React, when to use Redux, Basic login, NGINX, Docker, etc, etc, etc. My point is this: knowledge of Closure(Script) is a great tool in any programmers tool belt, but it is definitely not the most important one for a solid frontend engineer.