excluding features from sloppy mode

Brendan Eich brendan at mozilla.com
Wed Jan 16 11:31:33 PST 2013

There's no const in IE, so we are pretty sure we can take the hit of 
breaking "Mozilla" (non-IE branches, also WebKit, maybe Opera) code that 
uses const.


Brandon Benvie wrote:
> The incompatibilities between let/const as implemented in V8 and 
> Spidermonkey and how they're specified in ES6 are an additional factor:
> * Per iteration loop binding (V8 and Spidermonkey don't do this for 
> let/const).
> * TDZ. `x; const x = 10` works in V8 and Spidermonkey currently, 
> specified to throw ReferenceError in ES6
> I think there's other differences.

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