With the advent of WebAssembly, the race is on to bring new languages to the web. This is the first example (I think!) of a Ruby interpreter running in the browser.
The path to get there is circuitous.
Ruby script → MRuby bytecode → C → emcc → LLVM → Binaryen → WebAssembly
The good news is access to that path is just a
gem install wasm away. Read the entire post for some great context and history around these efforts.