Re: Changes in chrome JS code due to ES6 global lexical scope
I think that would fail as well, because the let would be shadowing the
global x, which isn't allowed.
On Sep 18, 2015 2:25 PM, "Neil" wrote:
> Shu-yu Guo wrote:
>
> Good catch and thanks for the correction! The take-home from the example is
>> that: due to the global lexical scope, a TDZ error could arise later due
>> to
>> newly introduced bindings.
>>
>> So for that I guess the code would have to look like this?
>
>
> var x;
> function f() { dump(x); }
> f(); // prints undefined
>
>
>
> f(); // throws TDZ error?
> let x = 42;
>
>
> --
> Warning: May contain traces of nuts.
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Re: Changes in chrome JS code due to ES6 global lexical scope
On 17/09/15 19:59, Shu-yu Guo wrote: > Because until now, our global 'let' semantics have been identical to > those of 'var', I have already landed a patch that mass replaces global > 'let' with 'var' as part of bug 1202902. I think someone should make you a "var is the new let" t-shirt... Gerv ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Changes in chrome JS code due to ES6 global lexical scope
Shu-yu Guo wrote:
Good catch and thanks for the correction! The take-home from the example is
that: due to the global lexical scope, a TDZ error could arise later due to
newly introduced bindings.
So for that I guess the code would have to look like this?
var x;
function f() { dump(x); }
f(); // prints undefined
f(); // throws TDZ error?
let x = 42;
--
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Re: Changes in chrome JS code due to ES6 global lexical scope
Good catch and thanks for the correction! The take-home from the example is that: due to the global lexical scope, a TDZ error could arise later due to newly introduced bindings. On Thu, Sep 17, 2015 at 7:34 PM, Boris Zbarsky wrote: > On 9/17/15 8:26 PM, Shu-yu Guo wrote: > >> The first call to f() does not throw. >> > > It actually does, because the bareword lookup for "x" fails. You get > "ReferenceError: x is not defined". > > If you replaced "x" with "window.x" or "self.x" or "this.x" or something I > think you'd get the behavior you describe. > > -Boris > > ___ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform > -- shu ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Changes in chrome JS code due to ES6 global lexical scope
On 9/17/15 8:26 PM, Shu-yu Guo wrote: The first call to f() does not throw. It actually does, because the bareword lookup for "x" fails. You get "ReferenceError: x is not defined". If you replaced "x" with "window.x" or "self.x" or "this.x" or something I think you'd get the behavior you describe. -Boris ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: Changes in chrome JS code due to ES6 global lexical scope
(Isn't that bananas, by the way?)
On Thu, Sep 17, 2015 at 5:26 PM, Shu-yu Guo wrote:
> On Thu, Sep 17, 2015 at 5:18 PM, Neil wrote:
>
>> Shu-yu Guo wrote:
>>
>> 4. The global lexical scope is extensible. This means dynamic scope
>>> (lol!):
>>>
>>>
>>> function f() { dump(x); }
>>> f(); // prints undefined
>>>
>>>
>>>
>>> let x = 42;
>>> f(); // prints 42
>>>
>>>
>>> Would you mind clarifying what this is supposed to demonstrate? It looks
>> to me that this is demonstrating TDZ semantics, and under ES6 the first
>> call to f() will throw.
>>
>
> The first call to f() does not throw. These are two separate
> tags, and during the execution of the first