I just don't understand this, even if students were asking for it. It's a poor language whipped up in a week or two - is it really what you want to base someone's first exposure to programming on?
What I wonder though is, what is the goal of the current class? If it's about teaching OO fundamentals, I can't imagine JS would be a better replacement for Java than Python. If you're just trying to teach concepts, sure JS is fine, but it just seems like Python would be all around better for instruction than JS.
Also, the direct applications of JavaScript are numerous: web scrapers, node bots, front-end, back-end, iOs/android applications and a lot more!
For people who look at programming as a medium of expression to build stuff, Javascript is a language that a computer can do a whole breadth of things with.