we shipped druntime on emscripten on the opend side almost two years ago, supporting everything but threads and exceptions (i tested on emcc 3.1.69, i heard a later version of emscripten broke, im not sure). see my blog post from release time: https://dpldocs.info/this-week-in-arsd/Blog.Posted_2024_10_2...

there's a contributor working with both upstream and opend adding wasi support as well, and he also got exception support working, we'll probably ship that next month.

so the full d story on wasm is progressing too.