> and Observable is cool, but strays from standard JS.

The front end does but the underlying runtime is running just javascript, and the source code is basically javascript with some trivial macros which are fully captured in the MIT licensed acorn parser. That's why normal Javascript debugging expression work perfectly in Observablehq.

https://github.com/observablehq/parser

I love the Observable runtime. I wrote a decompiler for it so you can bidirectionally convert between the front end source and the compiled pure JS representation.

https://observablehq.com/@tomlarkworthy/observablejs-toolcha...