excluding features from sloppy mode

Brendan Eich brendan at mozilla.com
Wed Dec 26 21:34:03 PST 2012


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.

See my followup to the offshoot thread Mark started, about "excluding 
features from sloppy mode", for clarification on new head syntax for 
functions not opting the body into strict mode. (Ditto for 'class' body 
strictness, IIRC; 'module' does imply strict body, in contrast.)

/be


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