Javascript let hoisting behaviour question

Asked Oct 14 '19 at 12:49

Active Oct 14 '19 at 13:15

Viewed 36 times

So I'm trying to run these 2 functions in chrome:

function let_test1() {
    debugger;
    let something = true;
    return something;
}

function let_test2() {
    debugger;
    console.log(something);
    let something = true;
    return something;
}

If in let_test1 I try to evaluate something at the breakpoint, I get undefined.

If I try this in let_test2 , I get a ReferenceError.

Any ideas why this happens?

CLARIFICATION

Not sure this is related directly to the TDZ answers since this pertains specifically to the first example resolving to 'undefined' instead of a 'Reference Error' and the question is what causes it. The TDZ in my understanding addresses the 'Reference Error' only.

Should so, why does it resolve to 'undefined' in the first example? As in my current understanding it should throw a ReferenceError.

edited Oct 14 '19 at 13:15

asked Oct 14 '19 at 12:49

overburn

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@SoumyaGangamwar `let` _is_ in fact hoisted – Nick Parsons Oct 14 '19 at 12:58
How ? any example can you provide – Soumya Gangamwar Oct 14 '19 at 12:58
@SoumyaGangamwar it's in the duplicate answer, the second block of code from the bottom: https://stackoverflow.com/a/33198850/5648954 – Nick Parsons Oct 14 '19 at 12:59

Javascript let hoisting behaviour question

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