Yeah, Richard's approach would be about eight times more elegant...if
there were something reliable to test for. It can be IE-specific, of
course. I was sure when I saw his post that there would be
*something* we could check for, but none of the things that come to
mind are both present (IE doesn't have arity) and sufficiently unique
(see Kangax's comments about call, apply, etc.). (BTW, don't try to
iterate the properties of an intrinsic function object using for..in
with IE6 on XP; Bad Things happen.)
Sadly my big list approach just won't work, it will always have holes
in it. For example:
var x = document.createElement("p");
if (Object.isFunction(x.getAttribute)) { ... }
So between the holes and the bloat involved in handling even the ones
we could handle, I'd say we just mention it in Object.isFunction's
docs and move on, until/unless someone finds the magic thing.
--
T.J. Crowder
tj / crowder software / com
On Jun 6, 12:51 pm, kangax <[EMAIL PROTECTED]> wrote:
> I wish it was that easy : ) Unfortunately, we can't really account for
> all host objects, which are notorious for their incompliance with
> specs (e.g. it's well known how some of them have no constructor
> property, and others throw error when accessing certain properties).
> Hardcoding few methods barely solves the problem.
> We could of course check for "apply/call" members on an object, but
> guess what - those are undefined as well : )
> As far as I remember jQuery calls object's toString, then tests if
> result contains "function". That's clever, but unreliable, as any
> other object which defines "toString" to return something that
> contains "function" will produce falsy results.
>
> - kangax
>
> On Jun 6, 6:08 am, "T.J. Crowder" <[EMAIL PROTECTED]> wrote:
>
> > OMG, I can confirm this, on IE6 anyway. (Couldn't they get *anything*
> > right? I mean, I know Firefox has its issues, but... And yes,
> > technically a function is an object, but that's no excuse.)
>
> > The only workaround that immediately comes to mind is to actually have
> > a list of these and compare against them in IE -- e.g.:
>
> > isFunction: (function(){
> > if (typeof window.close == "object") {
> > // IE version, works around typeof returning "object" for
> > intrinsic functions
> > return function(object) {
> > return (
> > typeof object == "function"
> > || object === window.close
> > || object === document.getElementById
> > // etc., etc., etc.
> > );
> > };
> > } else {
> > // Non-IE version, expects typeof to work correctly
> > return function(object) {
> > return typeof object == "function";
> > };
> > }
>
> > })()
>
> > Blech. The more of this that happens, the more I want a separate file
> > that only IE people have to download containing these workarounds...
> > --
> > T.J. Crowder
> > tj / crowder software / com
>
> > On Jun 6, 9:27 am, Viktor Kojouharov <[EMAIL PROTECTED]> wrote:
>
> > > Here's quite the problem in IE.
>
> > > For certain 'native' functions, like window.close, or
> > > document.getElementById, typeof for those functions returns on object
> > > in IE. Consequently, Object.isFunction will actually return false for
> > > those functions.
>
> > > Though there's probably little that can be done, I thought you guys
> > > should know about it.
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