A random collection of ES4 draft spec surprises and thoughts

Brendan Eich brendan at mozilla.org
Mon May 26 14:55:17 PDT 2008

On May 26, 2008, at 2:16 PM, Jeff Dyer wrote:

> On 5/26/08 12:01 PM, Brendan Eich wrote:
>> ActionScript also had read-only __proto__ in at least one of its
>> versions. I'm not sure if it still does in AS3.
> __proto__ is not supported in AS3, to my knowledge.

I was thinking of


So, ActionScript 2 -- right?

> Any anyways, if there is
> controversy here it should be that __proto__ is being reserved in  
> ES4 and is
> not as generally usable as in ES3 and ancestors.

(No __proto__ in ES3, of course.)

> Not, that it has special
> meaning at certain points in the grammar.

Mark's point about JSON, Doug has raised it too, is that magic  
property names in an ES standard, if not in a few implementations of  
ES3, pre-empt those names from being used as JSON property names.  
Even if the identifier __proto__ were not in the grammar -- if it  
were only the name of a magic Object.prototype getter -- it would  
break the JSON < ES4 relation. But I think that relation is already  
broken, since (AFAIK) JSON is not a subset of ES3.


More information about the Es4-discuss mailing list