"let", of course, is a retrofit to Javascript. So was "var". In the early days of Javascript, before "strict mode", few people declared anything and most variables had global scope.

It's really hard to get a declaration-free language right. Python was the biggest success to date.

Huh? `var` was not retrofitted. I distinctly remember it being there since I started learning JavaScript, like around '96. It is true that a lot of people were slack about using it, but that's just laziness, not that it wasn't there.

Sorry, what I meant was more that since we have let, there isn't any good reason to use var anymore. I definitely don't advocate the thing in this article where he eliminates var usage by littering the code with IIFEs.

Lisp?

I believe the parent comment was referring to using “let” instead of “var” - “let” supports reassignment.