The first ECMAScript.next features in Firefox and Chrome
Update 2012-01-23: “ECMAScript 6 support in Mozilla” on the Mozilla Development Network.
The next version of ECMAScript (code-named ECMAScript.next ) will be standardized by 2013. This post enumerates the first features that are currently being tested in Firefox and Chrome.
Dave Mandelin mentions Mozilla’s ES6 planning page
. He points out the following highlights (paraphrasing an email of his):
The block-scoped let
have been available in Firefox for a long time.
V8 (Chrome, Node.js)
on Google+ provides details on V8. Quoting François Beaufort:
A code search
suggested by Paul Irish shows the relevant flags:
DEFINE_bool(harmony_typeof, false, "enable harmony semantics for typeof")
DEFINE_bool(harmony_scoping, false, "enable harmony block scoping")
DEFINE_bool(harmony_proxies, false, "enable harmony proxies")
"enable harmony collections (sets, maps, and weak maps)")
Andreas Rossberg elaborates
... the --harmony flag currently activates the following experimental features for V8:
On the browser side, that should become functional in Chrome 17 (some of it is in 16 already, but incomplete/buggy) by setting
If you are on the Chrome dev channel, you should also see it show up on chrome://flags soon.
- A brief history of ECMAScript versions (including Harmony and ES.next)
- ECMAScript.next: the “TXJS” update by Eich
- es6-shim – ECMAScript 6 functionality on ECMAScript 5