Why does typeof NaN return 'number'?

Question

Just out of curiosity.

It doesn\'t seem very logical that typeof NaN is number. Just like NaN === NaN or NaN == NaN returning

Answer 1

We could argue that NaN is a special case object. In this case, NaN's object represents a number that makes no mathematical sense. There are some other special case objects in math like INFINITE and so on.

You can still do some calculations with it, but that will yield strange behaviours.

More info here: http://www.concentric.net/~ttwang/tech/javafloat.htm (java based, not javascript)