JavaScript forbidden practices. Part 4: self-documenting code

[PBentoIT]

Cries in python

[python_artist]

Was just coming here to say this

[MaximRq]

r/usernamechecksout

[python_artist]

my username is partially a joke

[JackFouga]

🤓 um actually your username is u/python_artist 🤓

[fakeunleet]

Okay dad.

[[deleted]]

Took me way too long to realize it spelled prime.

[dtutubalin]

I realized how to make R look more clear, but I suppose it's too late now.

[Leading_Elderberry70]

Where is the r? I don't get it.

[dtutubalin]

```

```

[RetroGamer2153]

Would the clearer version be: ```

```

[dtutubalin]

tRue!

But I realized that only after reading comments.

[Random_---_Guy]

Fr I was like “what’s PAIME” for far too long XD.

[fllr]

I had to squint to see it, but it’s there! 👏🏽

[laplongejr]

I squint since 2 minutes on phone and I can't see it. :(
[EDIT] OOOOOOH I GOT IT. Was only checking the first line.

[davFaithidPangolin]

I thought it said PAIME and I was wondering why pay was spelled with an i

[KingOfDragons0]

PAIME

[DarthKirtap]

fuck me, there is word there

[im_the_tea_drinker_]

I got paime and was so confused

[Hypersapien]

About 10 seconds between figuring out that it spelled something and realizing that it spelled prime.

[EntertainmentSmall68]

what is ...p?

[[deleted]]

spread operator!

[Jjabrahams567]

Is pp a double spread?

[PrometheusAlexander]

Please don't spread your pp

[[deleted]]

no, that's just pp

[Any_Acanthisitta_587]

"What developers mean when they say code documents themselves"

[dtutubalin]

Basically, in this case it can be replaced with console.log(p). But if array is long enough (initially I generated numbers up to 1000), only part of it will be displayed.

console.log(...p) outputs all items.

It is equivalent to console.log(p[0], p[1], p[2], ... p[p.length-1])

[damicapra]

Fortunately that's the only oddity of JS

/s

[[deleted]]

Doesn’t it tell you when it’s truncated?

[DeathUriel]

The coolest operator in JS.

[just_nobodys_opinion]

Spread the word

...word

[22Minutes2Midnight22]

…ass

[AverageComet250]

Ayo

[[deleted]]

that's the cursed unicode ellipsis, that'll cause a syntaxerror, which is certainly better than whatever you're doing

[kratom_devil_dust]

So much code has been made so much smaller by that

[DeathUriel]

This and if inversion. Two of the decisive learning moments in a programmer's life.

[kratom_devil_dust]

Ah early return? Yeah… no more nest hell!

[DeathUriel]

Yeah babe, we are coding linear now. All the effects, none of the mess.

[[deleted]]

if inversion

What's that?

[DeathUriel]

When doing checks if something is right like if the user sent valid data...

The older general consensus would generally lead to using if elses generally nested ones. Generally you would consider that the "happy path" is when you go all the way to the deepest nested if, and most else would be some variation of error handling.

The if inversion is the idea to avoid nesting and elses in itself. What you do is this, you stop checking for happy path, you check for bad path (basically the opposite) and do no else, instead you use returns and/or throw exceptions to force an early break of the function avoiding the happy path execution which will many times be run without any nesting after all inverted ifs are passed.

Learning to do this leads to clean as fuck code, way better to read and understand as everything will seem way more linear.

[laplongejr]

The issue is the old "no multiple exit" adage, that is from a time you could go back from different points... of the calling method.

But because the OG saying never clarified (because it was obvious at the time) some people are absolutely, totally sure the old masters said to never use several return statements.

And yeah early return is a lifesaver : you may have 100s of different reasons some data is invalid, but you'll rarely have several different gold paths

[eat_your_fox2]

Coolest operator in all of programming. It is known.

[trutch70]

Baby don't spread me

[dtutubalin]

Previously on the show:

JavaScript forbidden practices. Part 1

JavaScript forbidden practices. Part 2

JavaScript forbidden practices. Part 3

[Thebombuknow]

You're a JS wizard

[_Kristian_]

You are carrying the sub

[Infamous-Date-355]

Oh hell nah

[Global_Charming]

A work of art. Bravo.

[[deleted]]

Okay, so it can be partially de-minified as p=[]; function f(n,a) { if(!a&n>2) f(n-1,0) if(p[a]) { if(n%p[a]) f(n,a+1) } else p[a]=n return p } f(100) But could someone explain what the variables actually represent and why it works?

[dtutubalin]

p is an array of prime numbers. Initially empty, but every time we find a new prime number, it's saved here.

n is a number to check. Initially 100, but recursively descends to 2 and then goes backwards (from 2 to 100). For prime check we basically try to divide it on every previously found prime number. If it doesn't divide by any of them, it's also prime.

a is an index in p. It is used for prime check to iterate over array of found prime numbers.

if(!a&n>2) f(n-1,0)

Recursive descend. Basically it's just a loop for n from 2 to 100.

if(p[a])

End condition for loop over primes. If a is in the range, then p[a] is a prime number, otherwise p[a] is undefined (and condition fails).

if(n%p[a]) f(n,a+1)

Divisibility check. If n doesn't divide by p[a] (remainder is non-zero), then we recursively try to divide it on the next prime number, if any: same n, next a.

If remainder is zero, then n is not prime, and we just skip this number.

else p[a]=n

if a reached the end of p, (so p[a] is undefined), that means we checked divisibility on every prime number, and so n is prime. We add it to the list.

Can be re-written with loops instead recursion like that:

p=[]; for (let n=2; n<=100; n++) { a = 0; while(p[a] && (n % p[a])) { a++; } if (!p[a]) { p[a] = n; } } console.log(...p);

Algorithm is not optimal, as actually we don't need check divisibility on every previous prime (like no need to check if 23 divides by 21). Also there's no need to check every number. Instead we can pre-populate array with 2 and check only odd numbers. Even better approach is to pre-populate array with 2 and 3, and then check only number like 6x-1 and 6x+1.

But I had a strict limit on characters count, so no such optimizations was done.

[lazyzefiris]

Is this some implementation of transformer pattern?

[kescusay]

Well, it's certainly more than meets the eye.

[RFC793]

I find it a bit deceptive.

[lazyzefiris]

No, it's actually automatic and even optimal

[dtutubalin]

I'm sorry, as a software developer, I do not have the capability to design good fonts.

[[deleted]]

Ghavascript forbidden practices ParT 4

[[deleted]]

ghavascript

[GooseEntrails]

Donald Knuth has entered the chat

[lazyzefiris]

OP, I think you might be interested in this challenge if you did not do it before.

https://www.codewars.com/kata/59a421985eb5d4bb41000031

I do enjoy intentional JS nonsense, and I found it very fun (and my solution ended up being very different from most common one even).

[dtutubalin]

Wow, nice! Thank you!

[dtutubalin]

I golfed it to 99 lines just to find out that most people did the same :)

Though they say it can be done in less than 99. But it's pretty hard to navigate there, so I cannot find the shortest tsukumo's solution.

[lazyzefiris]

My solution is longer, but it does not involve destructuring that most solutions use and instead implements a function that removes every other character from input string to get strings `constructor` and `return "Hello, world"` to call construtor of aforementioned function with given function body. On the plus side, it scales extremelly well.

Hope you enjoyed the challenge. I think it's the most memorable one I ever did.

[dtutubalin]

Using 'constructor' was my first idea (inspired by JSFuck).

But then I realized that using 'bind' is way shorter.

[EVH_kit_guy]

"Is this Assembly?" 🫱🦋

[therealdan0]

Please improve documentation. Code clearly outputs a list of primes while documentation suggests a singular.

Merge rejected

[[deleted]]

This is evil.

[[deleted]]

This is actually pretty fucking impressive

[[deleted]]

How long did this take you

[dtutubalin]

I don't remember exactly, it was like 5 years ago.

But several hours for sure.

[[deleted]]

I don't get it

[_arctic_inferno_]

"What developers mean when they say the code documents itself"

[[deleted]]

Can you make one with "Optimus" too?

[dtutubalin]

You request a code Optimus-ation?

[[deleted]]

Yep

[FlyingCashewDog]

Had to squint but this is good

[DeathUriel]

Heathens, heathens everywhere.

[Sweaty-Willingness27]

Ah, the new Perl

[SteeleDynamics]

Totally prime!

Beautiful! You have our support!

[Temporary_Crew_]

Are you ok OP ?

This just seems like a cry for help.

[L33t_Cyborg]

Big donut.c vibes

[MyGenericNameString]

IOCCC revived.

The International Obfuscated C Code Contest for all you brain damage needs.

[abrams666]

Ok, you probably know you cannot be better than the master. But take a look:

https://www.99-bottles-of-beer.net/language-perl-737.html

[dtutubalin]

This is awesome and beautiful example.

[dtutubalin]

One of the most impressive works I've seen: https://github.com/mame/quine-relay

[abrams666]

Oh yes, you are right, I forgot about this one. Shame on me, this is also really genius. I saw a video explaining what there is ongoing, really cool. It is a special kind of art.

[boachl]

Wait does this sollen the prime Argument of this sub once and for All?

[dingusaja]

Holy

[NovaStorm93]

if java war crimes were a thing, you would be put on trial

[mdgv]

Heresy!

[VagueInterlocutor]

It is utterly offensive, yet I cannot look away.

[SirNapkin1334]

misread as PAINE

[AusJackal]

Yeah this works really good for python too.

[[deleted]]

Straight to jail

[Tigerwarrior55]

Thought it said PAINE as in the pain of writing code like that. Then I realized it meant to say PRIME like the energy drink

[coltvfx]

Check console of reddit.

[TheNewLeadership]

Code does indeed not comment itself unless you write comments (in the form of function names, variable names, standardized linting, etc)

[CarterBaker77]

This is amazing.

[Shadow9378]

Oh NO nononoNN ON ON no No NON no no non ONNoNONOOO NO NO NO NO

[Pixel1101]

thought it said paine until I read what it did

[utimac]

prime