NaN !== NaN is intended, and is the same in any other language that has NaN. It is never supposed to be equal to anything else, not even itself. As for the res

NaN !== NaN is intended, and is the same in any other language that has NaN. It is never supposed to be equal to anything else, not even itself. As for the rest of those quirks, they mainly have to do with type coercion, the rules for which are not as difficult to learn as the whole table in the submission. The fact that type coercion is performed for == is why nobody uses ==. You also should never try + or * on arrays (and why would you?). With some simple best practices, you never end up running into most of these quirks in practice.