this post was submitted on 17 May 2025
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Which of these javascript expressions is false? (lemmy.ml)
submitted 3 days ago by [email protected] to c/programmer_humor
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[–] [email protected] 84 points 3 days ago (6 children)

I'm no expert and I know that javascript is full of wtf moments, but please.. Let it be B

It's not gong to be B, it's it.

[–] [email protected] 12 points 2 days ago

Narrator: "It wasn't B."

[–] [email protected] 98 points 3 days ago (2 children)

It is true. Math.min() returns positive Infinity when called with no arguments and Math.max() returns Negative Infinity when called with no arguments. Positive Infinity > Negative Infinity.

Math.min() works something like this

def min(numbers):
  r = Infinity
  for n in numbers:
    if n < r:
      r = n
  return r

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.

[–] timhh 3 points 2 days ago

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.

[–] [email protected] 35 points 3 days ago (1 children)

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

[–] [email protected] 9 points 3 days ago (1 children)

The language not being compiled has nothing to do with error handling. You could have a min function that operates on dynamic arrays (e.g. std::min_element in C++ or min() in Python).

[–] [email protected] 4 points 3 days ago (2 children)

Not having a separate compilation step absolutely affects error handling. With a compilation step, you can have errors that will only be seen by and must be address by a developer prior to run time. Without one, the run time system, must assign some semantics to the source code, no matter how erroneous it is.

No matter what advisory "signature" you imagine for a function, JS has to assign some run time semantics to that function being called incorrectly. Compiled languages do not have to provide a run time semantics to for signatures that can be statically checked.

[–] BatmanAoD 1 points 2 days ago (1 children)

Without one, the run time system, must assign some semantics to the source code, no matter how erroneous it is.

That's just not true; as the comment above points out, Python also has no separate compilation step and yet it did not adopt this philosophy. Interpeted languages were common before JavaScript; in fact, most LISP variants are interpreted, and LISP is older than C.

Moreover, even JavaScript does sometimes throw errors, because sometimes code is simply not valid syntactically, or has no valid semantics even in a language as permissive as JavaScript.

So Eich et al. absolutely could have made more things invalid, despite the risk that end-users would see the resulting error.

[–] [email protected] 1 points 2 days ago (1 children)

Python also has no separate compilation step and yet it did not adopt this philosophy

Yes. It did. It didn't assign exactly the same semantics, but it DOES assign a run time semantic to min().

[–] BatmanAoD 3 points 2 days ago* (last edited 2 days ago)

I'm addressing the bit that I quoted, saying that an interpreted language "must" have valid semantics for all code. I'm not specifically addressing whether or not JavaScript is right in this particular case of min().

...but also, what are you talking about? Python throws a type error if you call min() with no argument.

[–] [email protected] 0 points 2 days ago (1 children)

I agree, compiled languages prevent large classes of errors, including invoking functions with wrong parameters. However, whether or not you define calling max() with no arguments to be an error or not is unrelated to your language being compiled or interpreted. You could define max() to be -inf in C++ if you wanted, even though the language allows you to prevent invocations of max() with no arguments altogether.

[–] [email protected] 1 points 2 days ago

The run time still has to assign a semantics to it, even if that semantics is a fatal error. In a compiled language, you can prevent the run time from having to assign any semantics by eliminating the error condition at compile time.

[–] CameronDev 38 points 3 days ago* (last edited 3 days ago) (2 children) 
Math.min() == Infinity
Math.max() == -Infinity

Wtf is going on JS...

edit: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/min

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

[–] [email protected] 13 points 3 days ago* (last edited 3 days ago) (2 children)

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?

[–] CameronDev 14 points 3 days ago (2 children)

I am also not a JS dev, we possibly aren't brain damaged enough to understand the perfection.

[–] [email protected] 7 points 3 days ago (1 children)

Most people don't use JS because they think it's perfect... they use it because it's the language that works on web browsers... or because thier coworkers made something in it... or because the library that does what they want uses it...

[–] CameronDev 4 points 3 days ago (1 children)

For such a terrible language, it really has staying power...

[–] [email protected] 6 points 3 days ago (1 children)

JS is the machine code of the web. Fewer and fewer people might write it directly, but it will live as long as the web platform does.

[–] [email protected] 2 points 2 days ago (1 children)

Until some browser can make pages with Python, maybe.

[–] [email protected] 3 points 2 days ago (1 children)

Only if that browser somehow becomes overwhelmingly popular in a market segment BEFORE it gets JS support.

[–] [email protected] 2 points 2 days ago

Could make a transpiler for python -> js, and serve python to the browser with a fallback to js if the python isn't supported by the browser

[–] [email protected] 9 points 3 days ago (1 children)

I develop with JS? All I can say is I need more brain damage to understand where is out

[–] [email protected] 7 points 3 days ago

Just keep developing with it, you'll get CTE soon.

[–] [email protected] 1 points 3 days ago* (last edited 3 days ago)

All functions built with function name(args) { body } syntax have a length based on the form of args. Other ways to create functions might set length (I'm not sure). Most of the functions provided by the runtime environment do have a length, usually based on the number of "required" arguments.

[–] [email protected] 2 points 2 days ago

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

[–] moomoomoo309 30 points 3 days ago* (last edited 3 days ago) (1 children)

It's C, NaN is never equal to itself in floating point, that's not just a JS thing.

[–] [email protected] 11 points 3 days ago (1 children)

Yep, it's C

[–] [email protected] 21 points 3 days ago

No, it's JS

[–] [email protected] 10 points 3 days ago* (last edited 3 days ago) (3 children)

I also am not familiar with javascript anymore....precisely because of this, exact, insane bullshit.

B... and/or C... evaluating as FALSE are the only things that... should even kind of make sense, according to my brain.

Though at this point in my life, I have unironically had a good number of concussions and contusions, so ... well you'd think that would help with JS development.

Javascript is insanity, and I am still convinced it is at least 40% responsible for Notch losing his goddamned mind.

'null' is somehow an object. because fuck you, thats why!

Is... 0 == '' ... is that two single quotes ' ' ?

Or one double quote " ?

If... it is one double quote... that wouldn't even evaluate, as it would just be an empty string without a defined end...

But if it was two single quotes... that would just be a proper empty string... and because of forced type coercion, both 0 and '' are FALSE when compared with ==, but not when compared with ===, because that ignores forced type coercion...

https://www.w3docs.com/snippets/javascript/when-to-use-double-or-single-quotes-in-javascript.html

Oh my fucking god WHY?!

Just fucking use one special character to delimit strings!

Don't have two that don't work together and also behave differently even when you pick just one of them... GraaaghhH!

brb, figuring out where Larry Ellison lives...

[–] [email protected] 4 points 3 days ago* (last edited 3 days ago) (2 children)

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'

[–] [email protected] 5 points 3 days ago

Douglas Crockford has a whole chapter of these in his latest book. There's also this classic video.

[–] [email protected] 4 points 3 days ago

Number = IEEE-754 double precision float, which includes NaN, so it makes sense

[–] [email protected] 4 points 3 days ago (1 children)

Notch? The guy who codes in java?

[–] sukhmel 3 points 3 days ago (1 children)

That's just short for JavaScript, isn't it?

[–] [email protected] 3 points 3 days ago

Java is actually twice faster cause the name is twice shorter

[–] [email protected] 2 points 3 days ago

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.

[–] KindaABigDyl 11 points 3 days ago (2 children)

Fun fact, even tho B is False, Math.min > Math.max is true

[–] CameronDev 20 points 3 days ago

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

[–] [email protected] 6 points 3 days ago

But B is true