Ask HN: Good library for a web-based REPL?

I'm working on a programming language implementation, and I'd like to offer a web-based REPL so people can try it easily. Frontend is not really my area, so maybe I didn't use the right search keywords. But an online search only revealed what seem to be single maintainer, fairly outdated jQuery plugins.

Does every try<language> website out there just implement its own REPL? Seems like a ton of work.