Not dead, just evolving! I hope to bring some of the insights from doing the k version into the free JS version. But even then, the formula language is unlikely to be raw JS - maybe jq, or a k subset. JS, as a moving target, is just too hard to parse in a small package.

Mesh's backend sits in one giant file because that's how we can write it in a Mesh sheet. But unfortunately the JS parsing library is huge and forms the bulk of the code. Happily, the k version is currently ~100 lines excluding tests.

If JSX were used, would the code need to be compiled? Mesh used to have a compilation step but it just added complexity (config files, build process, increased download size). Keep it simple! React.createElement is fine.