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Comment by Macha | Hacker News Reader

I guess the point is that:

    // line 1
    { 
       // line 2
       let x = 5; // line 3
       // line 4
    }
    // line 5

What is the actual end language user difference between saying the scope of x is lines 2-4 but magic (TDZ) makes it unavailable on line 2 vs. saying the scope is from line 3 to 4 with the TDZ being an implementation detail?

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One case where the distinction matters is this:

    function x() {
      console.log(a);
    }
    let a = 10;
    x();

If you thought 'a' was only in scope on lines 4 and 5 of the above snippet, you might assume that this snippet would return an error, but it doesn't; it prints 10. That's why it's a temporal dead zone, not a lexical dead zone.

That being said, I agree this is a weirdly overemphasized aspect of ES6. The TDZ is not some weird mysterious boogeyman. It's the thing that makes sense in nearly all cases.

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