This compiles JavaScript, replacing every single expression with a yield form that yields the expression and other useful debugging info. I wrote a VM that executes this special code, and allows you to break and step through code.

Essentially, I've stolen control of the stack, but let JavaScript take care of data and all the other complicated stuff.

Note: This is starting to be shared across the web, but this is just a proof-of-concept. I plan to make this robust and build an online code editor with it.