I wrote a tool to do that about 12 years ago. You still need to modify it a bit but you get a big bang for your buck

https://github.com/kristopolous/_inject

You can basically wander around any function context at any arbitrary time and see what happened. It exploits the reference counter to keep the contexts from being destroyed. It was really great back when I did a lot of client side js

The killer app version of this would be to open a repl at any context. As it stands it requires a good bit of competency to do it well.