There are a number of JS-in-JS stepping interpreters posted in this thread, one of which I've worked on :) For people who like this sort of thing, I think tail

There are a number of JS-in-JS stepping interpreters posted in this thread, one of which I've worked on :) For people who like this sort of thing, I think tailspin [1] is a particularly interesting example, since it supports reversible execution as well. [1] https://github.com/wthimbleby/tailspin https://github.com/wthimbleby/tailspin