Rust Lang + Wasm is an internet love story.

A good selection of games have already come out using WASM and rust.
My personal favorite is:
http://www.luduminis.com/pascal/

You can also compile languages such as c and c++, c# or python.
But I have no idea how garbage collection will work though for c# and python.
But I think rust will succeed better than most of the other languages.