I only needed only a subset of the spec, but with a negotiated subprotocol. I couldn't find a client library that worked for this in the browser, they all depended on node.

Normally I would write this in rescript, which has the same type system and ML heritage, and which I still love. But my sense is that rescript is floundering and gleam is growing in popularity & capability, so I'm eyeing gleam for an eventual replacement.