[HKayn]

JavaScript's behaviour in this case is consistent if we accept that JavaScript would always rather compute the next-best gibberish than throw an error.

While `1 / 0` is not a valid operation, it can be interpreted using limits. If `x` approaches 0, then `1 / x` will approach `Infinity`, hence JavaScript's result of this operation.

But with `0 / 0`, there is no unambiguous interpretation, so JavaScript defaults to `NaN` as its indicator for when a number is expected, but not received in valid form.

I'm not defending this behaviour of the language, just pointing out that there aren't "two different ways" of wrong behaviour at display here.