Subj : Re: Spidermonkey: Incorrect NaN comparison
To   : netscape.public.mozilla.jseng
From : Robert Ginda <rginda@netscape.com>
Date : Fri May 16 2003 01:15 am

See section 11.9.3, step 5, which states that NaN == NaN is always 
false.  To test for NaN, use the builtin isNaN function, described in 
15.1.2.4.


Rob.

Corey Murtagh wrote:
> Trying this:
> 
>   print(Math.floor(undefined) + " " +
>       Math.floor(undefined) == NaN)
> 
> produces:
> 
>   NaN false
> 
> So, it appears that NaN values returned by the Math functions are non 
> comparable to the NaN constant.  According to E262-3 (section 8.5):
> 
> "... to ECMAScript code, all NaN values are indistinguishable from
> each other."
> 
> I read this to mean that any of the 9007199254740990 (according to 
> E262-3) possible NaN values should be equivalent.
> 
>

.