Number.isNaN

Axel Rauschmayer axel at rauschma.de
Thu Dec 13 20:26:16 PST 2012


Honest question: I have yet to see boxed values in practice. Are there any real use cases?

[[[Sent from a mobile device. Please forgive brevity and typos.]]]

Dr. Axel Rauschmayer
axel at rauschma.de
Home: http://rauschma.de
Blog: http://2ality.com

On 14.12.2012, at 05:18, Luke Hoban <lukeh at microsoft.com> wrote:

>>> From: Mark S. Miller [mailto:erights at google.com] 
>>> 
>>> In that case, the current spec is wrong. The purpose of introducing Number.isNaN is to repair the >> following bug in the global isNaN:
>>> 
>>>    isNaN("foo") // returns true
> 
> Indeed, as Yusuke noted on the other reply, I referred to the wrong 'isNaN'.  And as you note, the point of the 'Number.isNaN' variant is to avoid any coercions.  
> 
> That still leave's JDD's original suggestion to allow Number.isNaN(Object(NaN)) to return 'true' by checking for either primitive or boxed Number.  It feels a little odd to introduce another kind of limited coercion into the language, but perhaps it is practically valuable to not differentiate boxed and unboxed numbers here?
> 
> Luke
> 
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