iteration order for Object

Jeff Walden jwalden+es at MIT.EDU
Thu Mar 10 18:45:24 PST 2011


On 03/10/2011 06:11 PM, Boris Zbarsky wrote:
> You may want to read <https://bugzilla.mozilla.org/show_bug.cgi?id=594655> and <https://bugzilla.mozilla.org/show_bug.cgi?id=611423>. People are running into performance issues due to lack of such special treatment today.

Further to these points, it is possible that Firefox might change its property storage system to address bugs like these such that property enumeration order changes.  This would be <https://bugzilla.mozilla.org/show_bug.cgi?id=586842>.  I am not saying anything about how likely or unlikely this is.  I haven't really started to research the problem or brainstorm about potential solution space yet.  But we do see problems with arrays with non-index, non-length properties, and it's certainly possible that a fix which permits extra, non-indexed properties to be added to arrays without notably de-optimizing property storage, and subsequent property access, may affect property enumeration order.

Jeff


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