excluding features from sloppy mode

Brendan Eich brendan at mozilla.com
Wed Dec 26 21:38:49 PST 2012


Brendan Eich wrote:
> Axel Rauschmayer wrote:
>>>> * const
>>>
>>> Already reserved (in some sense, even if equated to var in Opera), 
>>> no opt-in required. This identifier was reserved in ES1.
>>
>> But for
>>      const <x> = <y>
>> const is opt-in for <x> and <y>, right? Not sure that that makes much 
>> of a difference, though.
>>
>
> How could it matter? We are not changing runtime semantics (a la ES5 
> strict mode). Any new syntax in <x> or <y> is its own opt-in.

I just remembered that we did accept one runtime semantic change (which 
improves the language by having static semantics for where completions 
can come from): 
http://wiki.ecmascript.org/doku.php?id=harmony:completion_reform.

But this proposal won't affect <x> and <y> in your example. It is 
observable only via eval or equivalent.

/be


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