In #337 (comment) I mentioned that stack install does not copy the generated files over for ghcjs projects.
I think it might make sense to make it work out of the box, and there it was mentioned to maybe open a separate bug, so that's it.

However while I'm at it, I also have a related question. Since it doesn't copy the files for me, I decided that I'll do it myself with a custom Setup.hs and a cabal Build-type: Custom, but my Setup.hs doesn't seem to get invoked. Looking a bit with strace, I'm actually wondering if ghcjs is not invoked in place of ghc for the Setup.hs, and if that is the case, I'm wondering whether it's a good thing or not?