Of course both projects have the same maintainer if I recall, Jens Axel Søgaard is a rockstar :)
Original developer of Whalesong was Danny Yoo. https://www.hashcollision.org/whalesong/
There was also this: https://docs.racket-lang.org/racketscript/
Dave Herman worked on various JS-related libraries for Racket (or PLT Scheme) before he was involved with Rust.
- Modules aren't implemented yet, but are high on the list
- Continuation-based control flow isn't supported yet, including break and promises. Tail calls are supported though.
- No support for complex numbers, bignums, weak hashtables, immutable hashtables, prefab structs, regexp, or file I/O support
Most of the rest of racket/base should work, according to the README. There's also a FFI for javascript, including bindings for Math, DOM, Canvas, MathJax, XTermJS, and JSXGraph. Overall feels like you can use most of the language right now unless you need odd Racket-isms or call/cc.