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I am stuck with this peculiar scenario mentioned below. Could someone please explain to me what's the reason for the following behavior.

Why is Infinity - Infinity results NaN, but NaN === (Infinity-Infinity) results false ?

Anantha Raju C
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manju4ever
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    because `NaN !== NaN`. – Cristian Lupascu Sep 27 '15 at 10:48
  • Infinity is sometimes defined as the ability to define a subset that doesn't include all elements but is also infinite. Substracting infinity from infinity doesn't give a set outcome and is therefor not a number. That said it's impossible to validate wether 2 things are equal if all you know is that both are not numbers. – DrunkWolf Sep 27 '15 at 10:56

1 Answers1

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The answer lies in the full form of NaN.
NaN stands for Not a Number.
Hence, if something is not a number, it cannot be compared or checked for equality.

Going mathematically, 

Infinity - Infinity = NaN   (1)

NaN == Infinity - Infinity  (2)

Here in (1) NaN holds a value that signifies the result is not quantifiable.

And in (2) you are checking the equality of 2 entities that are not quantifiable.

Hope that makes sense.

P.S. I know string values can be compared, but that is not the case with NaN.

akshaynagpal
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