You might try this one:

http://www.bramstein.com/projects/funcy/

It implements pattern matching in JS, with objects and closures. Not as convenient as first class support, but might be worth it.

Have you seen matches.js? https://news.ycombinator.com/item?id=4516576

I also really miss pattern matching and I think that JavaScript would be well-served by it or even minimally some sort of destructuring.