ECMAScript.next features in Firefox?

Andreas Rossberg rossberg at google.com
Mon Jan 2 02:37:40 PST 2012


On 25 December 2011 13:26, Axel Rauschmayer <axel at rauschma.de> wrote:
> Paul Irish did a code search for that:
>
> http://www.google.com/codesearch#W9JxUuHYyMg/trunk/src/flag-definitions.h&q=harmony%20package:http://v8\.googlecode\.com&l=109

To elaborate, the --harmony flag currently activates the following
experimental features for V8:

- block scoping, let, const, block functions
(http://wiki.ecmascript.org/doku.php?id=harmony:block_scoped_bindings,
etc)
- proxies, though not direct proxies yet (i.e.,
http://wiki.ecmascript.org/doku.php?id=harmony:proxies)
- maps and sets
(http://wiki.ecmascript.org/doku.php?id=harmony:simple_maps_and_sets)
- weak maps (http://wiki.ecmascript.org/doku.php?id=harmony:weak_maps)
- typeof null reform
(http://wiki.ecmascript.org/doku.php?id=harmony:typeof_null)

On the browser side, that should become functional in Chrome 17 (some
of it is in 16 already, but incomplete/buggy) by setting
--js-flags="--harmony". If you are on the Chrome dev channel, you
should also see it show up on chrome://flags soon.

/Andreas


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