Should host objects be able to have [[Class]] "Function", "Array" etc.?

Garrett Smith dhtmlkitchen at
Sat Nov 15 21:40:39 PST 2008

On Sat, Nov 15, 2008 at 5:19 AM, Mike Shaver <mike.shaver at> wrote:
> 2008/11/14 Maciej Stachowiak <mjs at>:
>> Specifically, we expose a "filter" property on CSSStyleDeclaration, in
>> support of the SVG filter CSS property. However, many sites test for
>> "filter" to detect support for MSIE's proprietary "filter" property, which
>> sadly has the same name but completely incompatible syntax. Thus, we return
>> this kind of magical undetectable string so if tests don't detect us as IE.
>> It works basically the same ways as Mozilla's undetectable document.all,
>> which we also support.
> Our undetectable document.all works by returning a different value
> from the property access depending on whether it's a "detecting" use,
> like |if (document.all)| -- we don't use a magic falsy object (which I
> think is a violation of E262, but I'd have to dig into the ToBoolean
> bits to be sure).

It is common knowledge that the "undetectable" document.all is
detectable through normal scripting practices.

"all" in document

The same is true for the filter property:-

"filter" in

webkit: true.

Standardizing an MSIE property that works differently than in MSIE
creates compatibility problems on the web. A better alternative would
be to use a different property name.

> Mike

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