There are such things already in existence, but they all seem outdated, incomplete, unsafe, or some combination of those. I’ll keep working on this for my embeddable widgets project but have to get back to other projects for the majority of my work time for now… :)
I’ve gotten it to a stage where I understand more or less how the pieces go together, and have been documenting how the rest of it will be implemented. Most of it for now is a straightforward implementation of the language spec as native modern JS code, but I expect it can be optimized with some fancy tricks later on. I think it’s important to actually implement a real language spec rather than half-assing a custom “JS-like” language, so code behaves as you expect it to … and so we’re not stuck with some totally incompatible custom tool forever if we deploy things using it.
Will post the initial code some time in the next week or two once I’ve got it running again after some major restructuring from initial proof of concept to proper spec-based behavior.