> I think you've misunderstood. There's nothing in my New Year's email about > "getting ES6 semantics" when you find an occurrence of a particular feature > (that kind of thing was just a side conversation in the mega-thread, and a > very ill-conceived one IMO). The proposal is that within the context of a > module, you get a few small changes to the semantics **for the code within > the module** -- and nothing else. There's no scanning for particular > features. There's no language version detection. There's no versioning at > all. ES6 is an update to the language like every other edition of ECMA-262 > has been. Browsers don't have ES3 modes and ES6 modes. They just have > ECMAScript.
Ah, that makes sense, the thread you mentioned got me confused. Then for language implementors, there are three modes/semantics: 1. module => ES6 – some changes break with ES5.strict 2. "use strict" => ES5.strict + all ES6 constructs that are backward-compatible 3. otherwise => ES3 + all ES6 constructs that are backward-compatible It’s a tiny bit messy, but I can see that for developers, the illusion of a single ES6 is more or less intact. Seems like the best possible solution. Given that most people are bound to use modules and given that they are a very convenient “switch”, wouldn’t it be best to introduce as many breaking changes via #1 now (as opposed to later, in ES7 etc.)? Especially removing window from the scope chain. Mark’s email [1] seems to suggest just two modes (#1 being a superset of #2 = subsuming it), but using module as a switch, distinguishing #1 and #2 might be worth it. [1] https://mail.mozilla.org/pipermail/es-discuss/2012-January/019195.html -- Dr. Axel Rauschmayer a...@rauschma.de twitter.com/rauschma Home: rauschma.de Blog: 2ality.com _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
