excluding features from sloppy mode

Brendan Eich brendan at mozilla.com
Sat Dec 29 13:06:49 PST 2012

Andreas Rossberg wrote:
> I haven't replied to this thread yet, because I feel that I already
> made all the same arguments repeatedly to no avail. ;)  However, let
> me reiterate one particular observation, which is that IMHO much of
> the discussion (and decision making) around 1JS, modes, and opt-ins is
> just mistargeted.

Could be, let's see.

> Namely, it is primarily based on the expectations and needs of
> _current_ users. Users that are aware of what's ES3 or 5 and who are
> about to investigate what's new in ES6. To those users, design choices
> like making new constructs opt into strict mode by default will not
> seem a big deal, even natural.

Glad to hear some concurrence.

> But that group will be irrelevant after a relatively short time of transition!

Who knows? "Relatively short time" will be measured in units of years, 

> ES6+ will stay much longer (at least that's what we are working for).
> Consequently, what should take precedence are the expectations and
> needs of _future_ users of ES. Those who will come to ES6+ without
> knowing nor caring about the colorful history of its earlier versions.
> For them, having various features locally change the semantics of
> unrelated constructs


Who ever proposed that? It seems a misunderstanding. No one is saying 
that, e.g., destructuring formal parameters, or a rest parameter, should 
flip the containing function into strict mode. Banning duplicate formals 
in no wise does that.

So what exactly are you referring to here, in the way of a live proposal?


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