Comment by sascha sascha on "You (may not) Know JS" | Hashnode

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sascha sascha

Apr 14, 2021

Nice article, good visualizations.

But your explanation of closures is not correct and it happens a lot. You are describing lexical scoping as far as I remember.

A closure "closes" the function.

function a() {
 let me = 0;
 function b(){
  me = 1;
 }

 return b;
}

let fA = a(); // function is still "in the memory"
fA(); // now it is getting removed "from the memory"

The final execution of b() by calling fA() closes a(). So the name isn't even that bad.

David Morais

Fullstack Developer

Apr 14, 2021

Hey 👋 Tks for reading and comenting

My example is minimalist, at best, but is still a closure, at least according to MDN's explanation. I have access to the outer function/scope variables while inside an inner function. I just happen to be in a theoretical global scope

Your example is correct, but I think fA() will remain in the memory heap until it's garbage collected.

David Morais

I don't think you are correct about your example being a closure - even according to MDN's explanation.

"a function bundled together (enclosed) with references to its surrounding state"

You took the bit about surrounding state, but ignored the bit about a function being bundled together/enclosed. Your example is just looking at global state - that isn't bundled, that is open to everyone to mess with. :)

I would update it anyway for teaching purposes, as the rest of your article is excellent IMHO.

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