[troxwalt]

Exactly this. I'm a very visual person in regards to getting things done. Being able to see how a function works, would be delightful.

[oseibonsu]

Not a perfect solution, but this allows you to see how the computer executes a JS code. Hit the forwards and back buttons: http://pythontutor.com/live.html#code=function%20nested%28%2...