Totally agree with you. Some of the rebuttals below seem to be saying "But I use them differently!" Bully for them, but 99% of the time when it's not set, you

Totally agree with you. Some of the rebuttals below seem to be saying "But I use them differently!" Bully for them, but 99% of the time when it's not set, you don't really care why it's not set because it's not defined yet or because it's been set to `null`. And any time they assume it can only be null OR undefined but not either, there's a chance for a bug. Even if I "know" it can only ever be null and not undefined, it's safer to just say != null rather than !== null. Treating them differently in a code base is a legit semantic, but testing with != null works no matter the intended semantics.