[[Class]] and host objects
douglas at crockford.com
Tue Feb 10 12:26:29 PST 2009
> Other than toString I believe that the only directly
> user observable use of [[Class]] is the new Array.isArray
> function. The main use case for this was Doug's JSON
> libraries that needed to determine which objects should be
> output using array literal notation. We now have enough
> reflection support that he could write any sort of Array
> litmus test that he thought was appropriate (for example,
> length property value == largest numeric property name + 1).
> Given that, maybe we don't really need Array.isArrary which
> would probably simply the what does [[Class]]=="Array" mean
There are lots of other uses for an isArray test. Since we can't fix typeof,
Array.isArray is necessary.
The question is how does isArray work, does it look for [[Class]]=="Array" or
does it do something more mysterious. If we can settle on what [[Class]] does,
then that would seem better.
More information about the Es-discuss