const VS features detection

Brendan Eich brendan at
Mon Jan 6 08:53:07 PST 2014

David Herman wrote:
> On Jan 6, 2014, at 8:10 AM, Brendan Eich<brendan at>  wrote:
>> >  To further constrain design (since design is mostly about leaving things out), I will address the ES4-era |let (x = y, z = z /* outer z*/) ...| let blocks and let expressions, which came up recently. We should not revive these, given do expressions. do-exprs compose better with let and const (and other binding form) declarations.
> Fully agreed.

And as my example shows, this means there's no way of rebinding an inner 
z whose initializer depends on an outer z. When you need that, you'll 
need an arrow IIFE (IIAFE? AIIFE? yikes).


More information about the es-discuss mailing list