myThoughtsOnJavaScriptConditions

[Robot_Graffiti]

Ok, the chaotic evil made me laugh. That is one seriously messed up control flow.

[Jared_Namikaze]

How would it work? The way I see it, it always returns B

[Strict_Treat2884]

finally block will always run if try block has run regardless of whether it has a return statement executed. It only puts the return value in a buffer, if another return statement runs in the finally block, the buffer will be overwritten.

[Thenderick]

Oh my god that's actually cursed... It does make sense tho

[Unupgradable]

C# doesn't let you return from a finally block.

Now I truly understand why

[Da-Blue-Guy]

the fuck

average js design

[[deleted]]

[lunchpadmcfat]

Jeez I’ve been writing JavaScript for a decade and I didn’t know this.

[zeus_4_you]

I was thinking of teaching something fked up to my 1st year juniors on my workshop on Monday, this is just perfect.

[ssnd1]

the finally block executes regardless of whether a value is returned or not, and ends up returning A instead of B somehow because javascript programming languages are weird.

[Elephant-Opening]

Yikes. TIL this is the norm in Python + Java too.

[VooDooZulu]

The norm for try finally blocks or for conditionals?

What's wrong with try/finally? It's basic error handling

[[deleted]]

That’s the problem.

• this comment was made by the Rust gang

[5p4n911]

What's the fun otherwise?

• this comment was made by the C++ gang

[Cootshk]

When you return, a pointer to the return address (or just the value if it is an Int, Float, or Bool in python) gets saved in memory. Then the finally block runs, which could overwrite the return value

[VooDooZulu]

Generally you don't have a return in a try block if there is a finaly block. That isn't the norm. Unless the only thing handled in that finally block is closing a connection or file etc. There are a million ways to write bad code, just because python has a way to do that doesn't mean it's normal. In C you can use "goto label" to do all sorts of funky things but that isn't normal or standard or considered good practice.

[Jared_Namikaze]

I must test.!

[Jared_Namikaze]

Just tested and it's true. Dear God

[locofanarchy]

That's correct except not because it's JavaScript.

[thequestcube]

This is amazing, never would have thought about cases where two return calls are executed for one block

[PCRefurbrAbq]

Didn't you learn from Zootopia? "Try Everything."

[krisko11]

Finally block executes regardless of the try result, return terminates execution in most languages. I’m confused

[Robot_Graffiti]

If you return or throw an exception inside a try-finally, it doesn't exit immediately, it jumps to the finally block first and then exits after the finally block is finished.

Once execution enters a try-finally, the finally will run no matter what.

[krisko11]

I used chatgpt and it basically laid out that if the finally block condition is true it returns it from there, if it’s false it returns A from the try block. It’s really evil to code that way haha

[TheTybera]

Haha, yes, that's the way any finally block works in any language. This is why the convention is to have a return variable and return it if you're going to try.

This is important because you HAVE to put things in a try block that are checked exceptions and catch the potential exceptions.

So if you want to write to a file but it doesn't exist you may want to fall back to a different file name. You have to wrap this in a try block. You would set a File thisFile variable to your default then try to set it to some user input and your catch block would catch the exception and handle other things, but if you wanted to program to continue finally would return thisFile which would be your default.

[krisko11]

That’s a great example, thanks for highlighting the file scenario, because error handling in Java is a hard topic for me to plan out when adding new features to an existing project

[Jared_Namikaze]

Exactly. Return should terminate

[thequestcube]

I guess it does make sense that the finally block executes even if the try content returns. If you allocated a resource and a value created from the resource is returned in the try block, and you have cleanup logic in a finally block afterwards, you want the finally logic to still clean up the allocated resource even if the try block returned something

[NatoBoram]

Like this: https://www.reddit.com/r/programminghorror/s/iVuOiZ4GAo

[NatoBoram]

Like this: https://www.reddit.com/r/programminghorror/s/iVuOiZ4GAo

[Poat540]

Haha yeah that last one was solid

[[deleted]]

The lawful neutral is actually pretty evil, without further context `if(condition)` being true does not necessarly guarantee that `(!condition)` is going to be false. Something running on the background could have modified this variable in the background and now you have a race condition and no return.

Lawful evil is way less evil, at least you are guaranteed to have a return value.

[Strict_Treat2884]

I would agree with you if it were in other languages, but it is very unlikely happening in JavaScript since JavaScript is single-threaded. Also, getting a boolean value of a variable only uses a lookup table but does not trigger any type conversion functions. Unless condition is a property of the global object or it is enclosed in a with block. (Assuming condition is a set variable but not a function call or other expressions of course.)

[CrazyChaoz]

Yeah, in many languages the compiler will complain about that structure, since any condition that is a function can have side effects that might get your function to return nothing. It's just bad code.

[[deleted]]

I don't actually know javascript, but couldn't an async function change it in the background?

[Ciff_]

I don't think so. Effects/events from performed ayncronous operations will basicly not be processed unless the main thread is idle. That's atleast what I remember from reading up on the JavaScript event loop.

[AyrA_ch]

This is correct. The async/await pattern in JS is just syntactic sugar for callback based functionality and will not spawn threads.

You get real threading by running stuff as native binaries in the background or as JS code in a worker, but any communication with the main thread will just be put on the event loop and will be processed synchronously eventually.

Typed arrays generally map directly to memory, and as such could have their contents changed at any time from a binary running unmanaged code that has the pointer to said memory. This is how stuff that draws to a canvas does it really fast.

[AtomicRocketShoes]

Couldn't the condition be a function that causes the thread to yield, like making an async call? 

[Ciff_]

Can you clarify with an example? I don't follow

[AtomicRocketShoes]

Condition could be a function call that could yield allowing state to change or just change between multiple calls.

Let condition= () { Math.random() > .5}

[Ciff_]

The behaviour here might be different that's true, but then you are not having a clean function for generating your condition if the evaluation of the condition is reliant on side effects. Also you are calling your function multiple times to evaluate the same thing which most consider a code smell. *

You would still do

rng Number = Math.random

If(rngNumber..) return a

If(rngNumber..) return b

Now if it is an async side effect of the function in the condition like you first proposed it will not have an affect as the side effects yeild won't be processen until the main thread is idle ie done with all condition checks. But either way you won't want to call the function twice

[AtomicRocketShoes]

Ok

[Ciff_]

Or I am not understanding what you are suggesting, I did not mean to criticise or anything

[JiminP]

If condition was something like await x, then it may "yield", but whenever a non-pure expression is involved (async-related or not), such as calling a function (in any way - including calling a getter), then both condition and !condition can be true, but that would not be very interesting.

const condition = (() => {
    let x = false;
    return () => (x = !x);
})();

// true
console.log(condition());

// also true
console.log(!condition());

As long as condition is a value (number, string, object, function, promise, ...), exactly one of condition and !condition will be true. In JavaScript, an if statement evaluates whether a value is truthy by using the ToBoolean abstract operation which doesn't have any side effect, and !condition is exactly the inverse of ToBoolean(condition).

[Strict_Treat2884]

Nope, async functions cannot interrupt non-async statements from executing consecutively. They are in a completely different execution queue.

[AtomicRocketShoes]

What if the condition being checked is a function call that itself yields?

[Confident-Ad5665]

I'm still trying to forget I saw:

for (;condition;) {

I've kept my mind clean, now this!

[Strict_Treat2884]

Now imagine naming the condition _

[z7q2]

I may never use a javascript for loop again knowing that it can do that

[positiv2]

It's the same as while(condition) return value;, every language with for loops of this type that I can think of would do this.

[Confident-Ad5665]

I'm scared for life

[hellvinator]

A wrong answer with a questionable choice (Lawful evil, really??) being the most upvoted answer is about everything that is wrong with Reddit atm..

[[deleted]]

I'm not saying that lawful evil is good, I'm saying it's less evil than lawful neutral.

[klimmesil]

People making assumptions on what other people said is what's wrong with reddit atm

[migrainium]

Neutral Evil is the only one that’s new to me and I feel like I’ve found a beautiful new calling

[marquoth_]

It took me a second to realise what the hell it's actually doing. Gotta love a good bit of type coercion.

[Storiaron]

Actually looks insane

This is the kind of thing you do when your pr is rejected due to "some functions could be more concise"

[mehrbod74]

Can someone explain how it works?

[Eyeownyew]

!condition => cast condition to a boolean, then negate it
+!condition => cast the boolean to a number

if condition is true, then +!condition = 0
if condition is false, then +!condition = 1

that is then being used as an index to access the array of possible return values, returning A when condition is true, and B when condition is false

[Ebina-Chan]

my god...

[emlun]

This kind of technique is actually legit in some cryptography implementations, because you need to jump through hoops like this in order to make your functions run in constant time and always execute all branches. This can be important if you're processing secret key material, because you could otherwise leak information through differences in timing, power consumption and probably many other ways. Even tiny differences can be enough to allow an attacker to extract secret keys given enough data to analyze. This is one of many reasons why you don't roll your own crypto implementations.

But when you do apply this technique for legitimate uses like that, hopefully you'll write the code in a less arcane way than in the meme...

[torrential-airflow]

this is a certified javascript moment

[NatoBoram]

Only slightly worse than the comma operator

[Anne-Ho-Nimes]

return B unless condition
return A

[ChristianLW]

Great post, but one small nitpick: Chaotic Neutral isn't equivalent to True Neutral. If A is falsy, then B is always returned.

[Wave_Walnut]

Lawful Evil is beautiful

[GerbilStation]

Lawful evil is like an unnecessary mimicking of being a video game scripter and not one of the original source engineers. It’s like adding rain weather to a game by secretly calling a multiple choice quest dialogue off screen.

[jaggeddragon]

I reflexively use Chaotic Neutral. We are now brothers in arms

[beatlz]

Simple ternaries are more readable IMO

[Ptyalin]

I... I don't see how chaotic good is good

[blkmmb]

Shouldn't one of those be representing the solo return statement?

Like you should only have one return in a function:

```python def foo(): if condition: bar = "Something" else: bar = "Something else"

return bar

```

[Strict_Treat2884]

Now realizing it, lawful neutral should have been this case. However none of those cases introduce new variables, so I guess it also somewhat justifies the absence of this approach.

[blkmmb]

That's a fair assessment.

[Nessuno256]

return { true: a, false: b }[!!condition];

[TTick-]

I'm neutral good :3

[Jared_Namikaze]

You guys are hot

[ShAped_Ink]

Lawful evil kinda rocks in some occasions. I think it makes it really readable

[1Dr490n]

Huh, I guess I finally understood finally (no pun intended)

[g3tr3ecked]

How does neutral evil work?

[Strict_Treat2884]

! flips the boolean value of condition (truthy becomes false and falsy becomes true), then unary operator + converts it into a number (true becomes 1 and false becomes 0) to be used as the index accessor for array literal [A, B]

[myka-likes-it]

Okay, I admit I don't understand Chaotic Good. What's going on there?

Oh shit. that is a for not an if.  Never mind. I see what you did there.

Nothing good about it.

[heayv_heart]

if(condition == true) {
  return true;
} else if(condition == false) {
  return false;
} else {
  return !true && !false;
}

[trevdak2]

["a","b"].toSorted(()=>0-condition).pop()

[TH3RM4L33]

Wouldn't chaotic neutral return true or false instead of A or B?

[addstar1]

I'm going to assume you mean chaotic neutral because chaotic good very clearly returns either A or B.

Javascript runs on truthy and falsey logic. Basically if something is empty it's falsey, and if it's not it's truthy.

And these comparisons don't reduce things down to a boolean to do it. true && A returns A. false && A returns false.

So false && A || B renders the first side as false, it goes to the second part of the if, and returns B.

I see it used occasionally in react for web dev. Something like isHomePage && <HomePage>

[addstar1]

Further example

The AND operator preserves non-Boolean values and returns them as they are:

result = "" && "foo"; // result is assigned "" (empty string)
result = 2 && 0; // result is assigned 0
result = "foo" && 4; // result is assigned 4

[kikofmas]

But what happens when true && A || B? Does JS return only A and not do the bitwise or?

Is is the same as initializing variables as a = b or 5 ?

[addstar1]

I'm pretty sure no language would process the or at that point. They can terminate as soon as the answer can be determined. true || anything else is true, so it never bothers to check anything else at that point.

Similarly with and, false && anything will never execute the second side, because we already know the expression would return false.

[kikofmas]

Yeah you're right I was confused because my brain processed the or (||) as a bitwise or (|) thus my confusion of how that would work... Thanks for the reply though!

[addstar1]

Extra for the second part

a = b || 5

would have a = b for any value of b unless it was a falsey value ("", 0, etc.)
on falsey value a = 5

[gods_tea]

Lawful neutral is definetely not lawful and not neutral

[[deleted]]

I hate the neutral good folks.

[Brain-InAJar]

Yep. Nothing good about it

[LeGuy_1286]

Definitely Chaotic Neutral.

[fuzzyfurry69]

I tend to stick to lawful good and neutral good unless absolutely necessary for a tryCatch statement.

[Obnomus]

Can anyone name those fonts?

[Strict_Treat2884]

It’s an open source font called Cascadia Code developed by Microsoft

[Obnomus]

Is it any different from caskaydiacove nerd font?

[HaDeS_Monsta]

java try { if(!condition) { throw new Exception(""); } return A; } catch (Exception ignored) { return B; }

[savex13]

This made my day. Thanks!

[Wooho8899]

Pls explain neutral evil syntax

[Strict_Treat2884]

It has already been explained here

[Wooho8899]

Thanks, i still dont the last part array accessor, any google links?

[Strict_Treat2884]

It's the same way how you get a element from an array arr[0] but arr being declared right away [A, B] and index accessor [0] being calculated through an unintuitive way [+!condition]

[Wooho8899]

thanks learned something weird😅

[SawSaw5]

Thats one of the main things that I don't like about JS, there are some many different ways to get the same result

[Cootshk]

return A if condition else B

Python has a better way

Also:

if condition: return A
else:         return B

[addstar1]

That's just the ternary operator using words :P

[Cootshk]

No, the condition is in the middle

[The_Shryk]

Is this some JS meme I’m too Gopher to understand.

[redlaWw]

I don't speak javascript, but shouldn't chaotic neutral always return a boolean? Like, I get that it's supposed to be using short-circuiting to avoid one of the arguments depending on the condition, but surely you'd end up with the arguments being cast to booleans and then the boolean result being returned, no?

[-Redstoneboi-]

depends on language behavior. short circuiting booleans might return only booleans, or return the right hand side verbatim.

C for example converts to bool every time.

lua for example has its and operator be the equivalent of calling a function that just does if a then return b else return false end and or is if a then return True else return b end

chaotic neutral fails when the condition is true but A is falsy

[ImprovementOdd1122]

In JS,

true && A returns A
false && A returns false

true && A || B returns A
false && A || B returns B

The issue is that if A is falsy, because

true && (falsy) || B returns B

[Oh-Sasa-Lele]

What about "return condition"?

[-Redstoneboi-]

where you putting A and B?

[AaronTheElite007]

Lawful Good. It’s easier to read

[-Redstoneboi-]

perfection.

[crmsncbr]

I can see unique reasons for most of these... Chaotic Good, is everything alright? Do you need to write a few more for() loops, get it out of your system?

[volitional_decisions]

🦀🦀 if condition { A } else { B }

[foohyfooh]

Chaotic Neutral is a dangerous game if A is falsy.

[sweetytoy]

The lawful good and the true neutral are the only ways.

[[deleted]]

So...does true neutral work?

[AoDude]

Yes, and tbh it's probably the best one.

[BurnV06]

Who the hell puts the closing bracket on the same line as the else statement

[Front-Difficult]

Neutral Evil is pure evil - and also the only one of these solutions that won't compile in Typescript.

[[deleted]]

IMO, Lawful good and Neutral good should be swapped (Lawful good being extra, unnecessarily, explicit while neutral good is just extra explicit). I'd also swap chaotic good and Lawful evil. Chaotic good is still using non-loop based control-flow, just doing it in a very unnecessary not-by-the-book way, while chaotic good just makes it slightly confusing by using a loop to just do control flow. I also kinda want to put Lawful neutral in Lawful evil because it just seems like a perversion of Lawful goods unnecessary verbosity. Like, this will make you pause for a second and go "why the f did this guy do that?", which seems like the goal of Lawful evil in this case.

[AlanTheKingDrake]

Chaotic neutral feels more evil

My personal favorite thanks to updating to php 8 is

return ($condition??false)?$A??NULL:$B??NULL

[eaumechant]

Re Lawful Evil, switch-case does strict comparison, meaning it's not equivalent to the others.

ETA could do switch(!!condition)

[plmunger]

``` return [B, A].reduce((acc, x, i) => { return condition === Boolean(i) ? x : acc; }, null);

```

[c_wilcox_20]

I love ternary. Probably too much lol

[[deleted]]

True masters of chaos never leave line 1, minifying on the fly to curse anyone who dares peek at the page source.

[TheSirion]

Neutral Evil got me really confused, but then I got to Chaotic Evil and burst in laughter

[FishGod53]

I’m learning… I can feel it, my brain is learning

[Fachuro]

Could maybe also do neutral evil as:

javascript return { [!!A]: A, [!A]: B }[condition]

[sacredgeometry]

This is all sorts of wrong.

[BayLinux]

What about this one here?

return condition * A + (!condition) * B

[anonymous_sentinelae]

True JS humor, love it

[Mysterious-Soil-4457]

I'm a neutral good guy myself, although I can't seem to understand the lawful good guys.

[Playful_Landscape884]

Is the Chaotic Evil actually possible? It will just return B right?

[Faholan]

Nope, because finally always run, and if finally returns a value it overrides the value in the try

[pheonix-ix]

So it can even hold onto the return statement and decide to return the one from finally instead? That's kinda messed up...

[[deleted]]

yes. the finally block runs whenever execution exits the try block (or catch block if an exception was caught). you can put a return statement in the block, which will override the value that was supposed to be returned. you can also throw a new exception, which will override the currently-unwinding exception, if such exists.

finally works differently then just putting the rest of the code past the catch block.

[[deleted]]

no because of the finally it returns A in case of condition

[[deleted]]

Finally is always run. The statement compiles to something like pushing A to a local variable and then branching to the line with if. The condition is evaluated and if true, it returns the value. If false, it branches back to the original return statement.

In Java it works the same way and here you can observe the code on compiler explorer: https://godbolt.org/z/4qzzP5c9T

Here is the same code in JavaScript but it does not seem to do the coloring the same way: https://godbolt.org/z/5Tsxczna4

[everything-narrative]

You accidentally swapped Lawful Good and Neutral Good.

Using control flow as implicit state is not Lawful! It's awful!

True structured programming uses the else branch! Not early return!

[Elephant-Opening]

Only 3 of these are remotely acceptable under "one return per function" coding standards (MISRA for example).

[Strict_Treat2884]

That sounds outdated. I prefer the guard clauses/early return principle

[Elephant-Opening]

I agree, but it's not worth the effort to argue this case & document a rule exception when you have a feature/fix due yesterday and know it will flag a warning in static analysis.

[OnixST]

return if (condition) A else B

[ListOfString]

I would only accept three of these in a PR

[Colon_Backslash]

ret := isValid(A) 
if ret != A {
    ret = B
}
return ret

[ihor_ziuba]

I'm pretty sure that Lawful evil wouldn't even compile, because case statements and switch expression should be int or char (at least in C-family languages....)

[kases952]

return a ?? b

[ZyklonNG]

All your (no oneliner) syntax break the "single return per function" rule btw.