Versioning?

Xavier MONTILLET xavierm02.net at gmail.com
Mon Dec 19 10:21:46 PST 2011


Why

use version 6;

and not

"use version 6";

? Just to be sure ES 6 code breaks in old browsers ?
And what do you mean by "opt-in for ES6" ? New syntax ? Everything in ES 6 ?

I'm thinking about weakmaps:
- on the one hand, you want to use native weakmaps when available so
you would want to "opt-in for ES6"
- but on the other hand, you could also implement a weakmap "polyfill"
that wouldnt be as efficient, that would suck the memory but still
work, and have it work in older browsers

Therefore, setting the thing to do to "opt-in for ES6" to something
not backward compatible doesn't seem like a good idea to me.

On Mon, Dec 19, 2011 at 1:42 PM, David Bruant <bruant.d at gmail.com> wrote:
> I did start a related thread a while ago [1].
>
> Brendan's response [2] explained a few things:
> "Please read RFC 4329:
>
> http://tools.ietf.org/html/rfc4329
>
> There will be *at least* a ;version=6 parameter you can use, probably
> with either application/javascript and application/ecmascript -- I have
> argued that we should align version numbers."
>
>
> "Beyond the RFC 4329 version= parameter, we also want a pragma for
> in-script-content version assertion:
>
>  use version 6;"
>
> See the full response [2] for full context.
>
> Besides an es-discuss thread, I think that what is really needed is an
> harmony proposal. How to opt-in for ES6 is outside of the scope of pure
> ECMAScript (especially if it's with playing with the HTML script tag
> @type attribute), but let's face it, web devs need this information and
> a wiki page on the topic would be handy.
>
> At the time of reading Brendan's response, I didn't have anything to add
> on that and I still don't. Unlike HTML and CSS, JavaScript needs new
> syntax features. Syntax features that are NOT backward compatible with
> ES3. If you use one of these features, your script break in older
> browsers (unlike new HTML elements and CSS rules).
> I don't see an alternative to versionning. Smarter people are welcome to
> jump in, I guess.
>
> David
>
> [1] https://mail.mozilla.org/pipermail/es-discuss/2011-August/016262.html
> [2] https://mail.mozilla.org/pipermail/es-discuss/2011-August/016267.html
>
> Le 19/12/2011 11:49, Peter van der Zee a écrit :
>> https://lists.webkit.org/pipermail/webkit-dev/2011-December/018924.html
>>
>> ``use version 6;``
>>
>> In which thread on esdiscuss should I have read about that?
>>
>> - peter
>> _______________________________________________
>> es-discuss mailing list
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>> https://mail.mozilla.org/listinfo/es-discuss
>
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