Which of these javascript expressions is false?

So, the language isn't compiled (or wasn't originally) so they couldn't make min() be an error that only a developer saw, it has to be something that the runtime on the end-user system dealt with. So, it had to be assigned some value. Under those restrictions, it is the most mathematically sound value. It makes miniumum-exactly-2(x, min(<...>)) be exactly the same as min(x, <...>), even when the "<...>" has no values.

As a developer, I see a lot of value in static analysis, including refusing to generate output for sufficiently erroneous results of static analysis, so I don't like using JS, and the language that I tinker with will definitely have a separate compilation step and reject the equivalent of min(). But, if I HAD to assign something like that a value, it probably would be a representation of infinity, if we had one (probably will due to IEEE floats).

HTH

I’m guessing there’s a reason they wanted min() to be able to be called without any arguments but I’m sure it isn’t a good one.

It not a totally unreasonable definition. For example it preserves nice properties like min(a.concat(b)) == min([min(a), min(b)]).

Obviously the correct thing to do is to return an optional type, like Rust does. But ... yeah I mean considering the other footguns in Javascript (e.g. the insane implicit type coersion) I'd say they didn't do too badly here.

Math.min.length is 2, which weakly signals that it's designed to handle at least two parameters

Why would they even define this value?

Note: I’m not a js dev, do most functions have length?

Its the min value of the input params, or Infinity.

And the reason it's Infinity If there is no input, for better or worse, under the hood the method is assigning a variable, min, the highest value possible and then comparing it to each element in the list, reassigning it when it encounters an element lower than its value at the time. So it will obviously always be reassigned if there are any elements at all (if they're less than Infinity, I guess). But if there are no elements, it's never reassigned, and thus returns Infinity. It could have just signed min to the first element instead if Infinity, but that would lead to a runtime error when min was run without a function. If you're not going to throw a runtime error though, it makes sense for min to return Infinity because, what other number could you return that couldn't actually be the minimum

Yep, it's C

I don't think my sanity can take all of these explanations.

Though I just spotted one that's worse than null being an object ..

typeof NaN
"number"

I mean, come on.. it's even in the fucking name!

Edit - fixed capitalisation in 'NaN'

It’s pretty easy to avoid all of these, mostly by using ===. Null being an object is annoying and is one of the reasons ‘typeof’ is useless, but there are other ways to accomplish the same thing.

JavaScript has a lot of foot guns, but it’s also used by literally everyone so there is a lot of tooling and practice to help you avoid them.

That is not a fun fact. How do I unsubscribe :D

But B is true

Javascript is basically just C with some syntactical sugar, right? RIGHT?!?

Math.min isn’t the minimum integer; it’s the minimum of a list (and max visa versa)… the min/max of an undefined list is the same… IDK what it is, but this probably the most reasonable of the “WTFs” they could have put there i think… other languages would throw an exception or not compile (which JS definitely SHOULD do instead of this, buuuuut lots of JS has aversions to errors)

*edit: okay the curiosity was killing me: Math.min() is Infinity and Math.max() is -Infinity

It also makes a lot of conditional expressions less complicated because comparisons of all kind against NaN return false.

Tony Hoare: "Introducing NULL was a billion-dollar mistake"

Brendan Eich: "Hold my undefined"

"This comparison appears to be unintentional"

It's not true in a normal programming language. If it is true in yours, you should stop using it immediately.

probably not true in most other langauges. although I'm not well versed in the way numbers are represented in code and what makes a number "NaN", something tells me the technical implications of that would be quite bad in a production environment.

the definitive way to check for NaN in JS would probably be something like

// with `num` being an unknown value

// Convert value to a number
const res = Number(num);

/*
 * First check if the number is 0, since 0 is a falsy
 * value in JS, and if it isn't, `NaN` is the only other
 * falsy number value
 */
const isNaN = res !== 0 && !res;

nah, it's more fun this way.