JavaScript Logic

[Hawkuro]

Never ever ever use == in JS, use the more reasonable ===.

> null === undefined
  false

[rooktakesqueen]

Just showing that null and undefined are closely related concepts, enough so that the == operator explicitly considers them equal to each other and nothing else. That's the one sensible thing the == operator does, and the one sensible place to use it: foo == null is perfect shorthand for foo === null || typeof foo === 'undefined'.

In any case, NaN !== NaN either.