NaN is 'not a number' A string is not a number A function is not a number If 'not a number' === 'not a number' then any string === any function

This is a joke...

Rules around NaN aren't Javascripts fault; it's IEEE floating-point idiocy that a given NaN doesn't compare equal to itself.

That is a corruption. It should never be the case that a thing is not itself.

You saw your chance and you took it. And for that, I respect you.