FYI, we have just landed an updated Object.isFunction few days ago. It
now returns false for regexp objects and works around WebKit's
NodeList issue.
http://github.com/sstephenson/prototype/commit/436a694dc1c30d3dc2bf262f63f8b34c65113439
As far as OP goes, first we all need to "define what a function is".
Is it something that implements call/apply? (then window.alert is not
the function)
Is it something that returns "function" when applied "typeof"? (then
window.alert is still not a function)
Is it something that implements internal [[Call]] property?
I'm more towards the third one, but then the method should be called:
"Object.isCallable"
The problem here is that although specs state that typeof should
return "object" for those expressions which DON'T implement internal
[[Call]], IE seems, once again, to go against the world.
- kangax
On Jun 6, 8:23 am, "T.J. Crowder" <[EMAIL PROTECTED]> wrote:
> 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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