iteration order for Object

Boris Zbarsky bzbarsky at MIT.EDU
Thu Mar 10 17:48:23 PST 2011


On 3/10/11 8:44 PM, Charles Kendrick wrote:
> It requires
> browser vendors to implement order preservation, such that we don't get
> the minor
> optimization that's possible from not preserving order at all.

For what it's worth, not preserving order for numeric properties allows 
optimizations that are decidedly not "minor".

You can compare the performance of "fast" and "slow" arrays in 
Spidermonkey to see the difference.

-Boris


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