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The author's explanation seems perfectly correct to me. Where does he "misunderstand block scoping vs lexical scoping"? By the Wikipedia definition:

> lexical scope is "the portion of source code in which a binding of a name with an entity applies".

...both `let` and `var` are lexically scoped, the scopes are just different.

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FWIW, I think the parent meant "function scoping vs lexical scoping" rather than "block scoping vs lexical scoping". You're correct that function scoping is technically a form of lexical scoping (where the scope is the function), but if you want to be _really_ pedantic, the ecma262 considers let/const to be "lexical binding"[0] as opposed to var being a "variable declaration"[1], where the former declares in the "Lexical Environment" while the latter declares in the "Variable Environment". These happen to be the same environment record on function entry.

[0] https://tc39.es/ecma262/#sec-let-and-const-declarations [1] https://tc39.es/ecma262/#sec-variable-statement

Thanks for the links, that adds a lot of important context.

However, there's no notion of the first example operating on a single scope and the latter on three different, individual scopes. Which is why scope ranges and where you declare a variable with `let` matters.

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