Mistaken example?

[nmaxcom]

Hi. At the end of the 2nd chapter you provide the following piece of code saying:

When the items variable is changed to reference another list of items, we’re in for a world of hurt—the todo API still works with the value items used to have, but items is referencing something else now.

var items = ['a', 'b', 'c']
var todo = checklist(items)
todo.check()
console.log(items)
// <- ['b', 'c']
items = ['d', 'e']
todo.check()
console.log(items)
// <- ['d', 'e'], would be ['c'] if items had been constant
function checklist(items) {
  return {
    check: () => items.shift()
  }
}

IMHO items and the checklist function are just forming a closure. So once that todo var is created and items is referenced to another thing, it doesn't matter what is done to items, it's irrelevant to the code.

I'm just a hobbyist so I thought someone should take a look at it.

[bevacqua]

@nmaxcom You're correct. The point I'm making here is that, if items were a const binding, you wouldn't be able to do items = ['d', 'e'] down the line. Thus, if items were const, it'd have a reference to the same array in the context of the checklist scope and the parent scope.

It's not an unsolvable problem, but you have to make sure the binding didn't change in order to keep treating the two as if they were the same. With const, in contrast, you can rest assured that the binding reference is the same as the one you passed down earlier, because you can't change it.