How is let compatibility resolved?

Brendan Eich brendan at
Wed Oct 2 09:58:21 PDT 2013

It would be easier if we had the other let-specific special forms, 
wouldn't it?

ES6 draft makes let a reserved identifier. This is not backward 
compatible, but we're trying to find out what we can get away with. The 
fallback if we can't reserve is to do what we will do with 'yield (not 
yet done in current drafts): contextually reserve via parameterized 
productions, so that in strict code and in module bodies, you can use 
'let' to declare (and in generator functions you can use 'yield' as the 


> Petka Antonov <mailto:petka_antonov at>
> October 2, 2013 2:47 AM
> Never mind, I just realized the let on MDN page is completely 
> different from ES6 let.
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