typeof fn === 'function'; // Some things like
document.createElement('object'); return wonky results
fn instanceof Function; // Breaks across iFrames
toString.call(fn) === "[object Function]"; // Works the same across
iFrames and returns more reliable results
~Daniel Friesen (Dantman, Nadir-Seen-Fire) [http://daniel.friesen.name]
Andrea Giammarchi wrote:
> About isFunction
>
> I lost the point where toString.call(obj) === "[object Function]" was
> introduced instead of obj instanceof function
>
> I understand differences in IE so I wonder if two distinct callbacks
> could solve the odyssey:
>
> isFunction: function( obj ) {
> return obj instanceof Function;
> },
>
> isDOMFunction: toString.call(window.alert) === "[object Function]" ?
> function( obj ) {
> return toString.call(obj) === "[object Function]";
> }:
> // IE only and only until standard native function manifest
> function( obj ){
> return !!obj && typeof obj.toString === "undefined" &&
> /^\s*\bfunction\b/.test(obj);
> }
> ,
>
> In this way we could consider that in every browser, and when
> call/apply are supported, isFunction(fn) will guarantee call/apply
> while a DOMFunction could require a try catch or a different behavior
> for IE
>
> switch(true){
> case $.isFunction(fn): return fn.call(what, ever);
> case $.isDOMFunction(fn): what.push.call(what, toArray(fn(ever)));
> return what;
> default: throw new Error("what tf?");
> }
>
> ... or maybe not?
> Regards
>
>
>
> On Sun, Jul 26, 2009 at 4:09 PM, Andrea Giammarchi
> <[email protected] <mailto:[email protected]>> wrote:
>
> I usually encapsulate toString from Object.prototype and if
> somebody breaks the rule it means we cannot trust anything
> included typeof. So, in few words, nobody has intersts into break
> this rule, imho.
>
>> On Jul 26, 2009 8:07 AM, "DBJDBJ" <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>>
>> Also, IMHO this yields high level of encapsulation of an important
>> mechanism.
>> Which is a good thing.
>> And it is a fraction of a micro second slower then
>>
>> Object.prototype.toString.call(x) === "[object Object]"
>>
>> but it is more compact ...
>>
>> In any case we are entering the subjective judgement phase, so I
>> think
>> we should stop here and leave it to jQuery team to use this or not...
>>
>> --DBJ On Jul 26, 12:09 am, Andrea Giammarchi
>> <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> > I miss the point about regexp usage ... please tell me the
>> difference (in a > real scenario) betwe...
>>
>> > On Sat, Jul 25, 2009 at 1:38 PM, DBJDBJ <[email protected]
>> <mailto:[email protected]>> wrote: > > > This indeed woks : functi...
>>
>
>
> >
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