ES6 doesn't need opt-in

Brendan Eich brendan at mozilla.com
Sat Jan 7 23:08:42 PST 2012


On Jan 7, 2012, at 11:05 PM, Brendan Eich wrote:

> Allen has 5&6, ES5, ES6, and Compat5. Relabel these to
> 
>   ES5-nonstrict-ES6-intersection
>   ES5-nonstrict
>   ES6
>   ES5-nonstrict-differs-from-ES6
> 
> Since ES5-strict is a subset of ES6, it doesn't require new states.

Again we wink at completion reform -- it changes semantics such that ES5-strict is not a subset of ES6 but we believe no code will notice (we could be wrong).

We give up on typeof null and removing the global object. The free variable analysis based on global properties still gives early error on typo wins. That makes the subset relation technically false too but let's also wink at it by considering only strict programs that reach runtime under either an ES5 or an ES6 implementation.

/be



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