for-in evaluation order

Boris Zbarsky bzbarsky at MIT.EDU
Mon Dec 27 03:42:24 PST 2010

On 12/27/10 5:39 AM, Michael Day wrote:
> Some quick testing with Firefox seems to show that for-in returns
> properties in the order they were added to the object

Yep; it's required for web compat, as you discovered.  When we 
accidentally broke it, we very quickly got bug reports.  ;)

> and some scripts  on the web (eg. RaphaelJS) seem to depend on that


> unless I'm
> horrendously misinterpreting them. This seems... bad?

Well, it's not bad except for ECMA's insistence on not specifying the order.

> Are objects implicitly ordered, by implementation convention?

For implementations that have to deal with the web, yes.


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