I was merely explaining why I downed your other comment. I don't care if you're a fresh bootcamp grad or the former lead on AdWords...your argument is equally compelling. I'm calling it out because I think it discourages people from engaging in conversations where they can learn. If you are who you say you are and have the experience I think you do and someone significantly more junior disagrees with you, it's an opportunity for you to explain your thinking in a way that helps them improve theirs going forward. Instead, you took an expedient and, IMHO, intellectually lazy route. It's a small thing, but it's all part of making our field more welcoming to newcomers. What JavaScript beginner is going to argue with the ex-AdWords lead? Beyond being an appeal to authority, your comment possibly shut down someone's positive learning experience.
And if it seems like I'm quibbling with you or being overly hard on what you've said, that part is definitely about who you are. I feel like those of us who've been in the industry a while (I'm a few years behind you, but I'm still nearing my 20th year doing this stuff) have an obligation to be better about technical discussions and work towards positive conflict, even if the other side seems intent on going negative. It's hard and I fail at doing it constantly, so I say this with the full realization that I'm often the proverbial 'pot' to your 'kettle'.
FWIW, I totally buy the former. If (null>0) returned null, then most things would still work as expected, and you could easily check the result of the comparison to catch unintended behavior. One can easily imagine a world where JS was defined this way from the start, and it'd be pretty much the same language.
The latter (three-way IF control structures) strikes me as waaaay more tenuous - much bigger change, more complexity on the programmer, and no benefits I can see that you wouldn't get from the former bit.
IF (x<y)==null {
[otherwise]
} ELSE IF (x<y) {
[then]
} ELSE {
[else]
}
For example, I suspect that three-way IFs like you describe would only really get used in two ways - often the second and third branches would be identical, and the rest of the time the third branch will be some kind of "console.warn('bad inputs!')" kind of error handling.
For the latter of those two cases, testing for the error case before proceeding to the regular logic (as in your code sample above) seems intuitively like the right thing to do - analogously to how you might check (isNaN(operand)) before doing some math. And in the former case, if the second and third branches are identical you'd almost certainly want some syntactic sugar to avoid writing the same logic twice, like "IF (bool) {...} ELSE-AND-OTHERWISE {...}" -- which would just be isomorphic to what we have now. You know what I mean?
FWIW, I actually agree with this. There's no need to add a new value. It would be fine with me (within the context of Javascript's already horribly broken design) to use an existing value (null or undefined) as the third "boolean" value.
The part that really matters is that whatever null>=0 returns it should be different from either 1>=0 or -1>=0.