Comment by jmull

Variable declared outside the loop construct lives outside the loop.

Variable declared inside the loop construct lives inside the loop.

Seems intuitive to me.

The complex thing here (and what seems to have confused the author) is the distinction between when the reference to the variable is captured vs. when the setTimeout() callback occurs.

Actually, this article shows what good shape Javascript is in. As it says, commonly deployed linters catch the really bad stuff, effectively deprecating those things.

Pretty much the rest of it to do with specific domains outside of javascript, like what actually is a character and IEEE floating point, or are rather out-of-the-way things like document.all and sparse arrays (not that people don't use sparse arrays, but it's entirely optional and if you're going to voluntarily go into that cave, I guess you must be happy to tangle with the bears living there.)