> On Oct 27, 2015, at 2:37 AM, Claude Pache <claude.pa...@gmail.com> wrote:
>
>
> Naturally, I meant:
>
> ```js
> Function.isGenerator = function (f) {
> return typeof f == "function" && f.toString().match(/^function\s*\*/) !=
> null
> }
> ```
>
> —Claude
>
>>
>> That function will work (in the sense of: will return an answer; I'm not
>> judging the quality of that answer) with anything reasonable fed to it
>> (where "reasonable" excludes things like `(class { static toString() { throw
>> "pwnd!" }})`). Well, ... until a proxy for a function is encountered.
>>
>> —Claude
This may have been pragmatically useful but it has never been a reliable test
because there was nothing that stops somebody from adding an arbiietrary
`toString` own property to f or from using dunder photo to change the prototype
used to supply `toString`.
Also, going back to at lest ES3, F.p.toString was specified to throw a
TypeError when applied to an object that “is not Function object”.
That said, I think it is plausible that the predicate in step 2 of
http://tc39.github.io/ecma262/#sec-function.prototype.tostring
<http://tc39.github.io/ecma262/#sec-function.prototype.tostring> could be
replaced with: IsCallable(func)
Allen
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