For WASM, there are interpreters written in Go:

https://shithub.us/slashscreen/ricket/HEAD/info.html

I'd love to have nethack/slashem, the terminal version, ported to it. No, not HTML+JS, VT220 output with colour at least, usable in any VT emulator with Ricket.

That way I would play Slashem everywhere without even needing to have an ANSI C+POSIX compiler with tons of Unix dependencies. 9front has some compat but the game looks like a maze of ifdefs for different Unix systems. GLHack can be compiled with NPE (a small POSIX+SDL2/3 wrapper) and TinyGL but for these games I'm faster with the terminal output.