[PATCH] More robust Object.isFunction

Just to clarify, Object.isFunction currently returns wrong results for regular expressions, most of the host functions in IE and NodeList's in Safari:

Object.isFunction(/foo/); // => true (regexp)
Object.isFunction(window.alert); // => false in IE (host function)
Object.isFunction(document.links); // => true in Safari (HTMLCollection)

The proposed function "fixes" regexp and NodeList glitches, but still returns false for host fucntions in IE

I dig it but you could make it smaller by:

isFunction: function(object) {  
  if (typeof object != 'function' ||
    typeof object.constructor != 'function') return false;  
  return Object.prototype.hasOwnProperty.call(object,'call');  
}

I don't know if the Object.prototype.hasOwnProperty.call route is better then the object.constructor.prototype.hasOwnProperty('call'),
the both take up the same amount of space.

Actually, it would get even more verbose : )

test = Function(); // instantiate a function

test.constructor.prototype.hasOwnProperty('call'); // => true
Object.prototype.hasOwnProperty.call(test, 'call'); // => false

afaik, functions don't have "call", but use the one from their prototype chain (i.e. Function.prototype). Invoking Object.prototype.hasOwnProperty in a context of a function obviously yields false.

What's funny here, is that we can't really trust hasOwnProperty of .constructor.prototype (i.e. it could have been augmented or assigned something else). Instead, we can call "original" Object.prototype.hasOwnProperty with the context of object's ".constructor.prototype" - but that's, imho, quite retarded.

// omg bbq wtf!
Object.prototype.hasOwnProperty.call(object.constructor.prototype, 'call');