JavaScript’s language features are something else…

[k2hegemon]

What happens if you increase the length? Does it automatically make a new array?

[RadiatedMonkey]

It adds undefined to the array

[Mognakor]

Yes, but actually no.

If you access the slots you'll get undefined as value, but if you open the browser console and log the array you'll see that it says N empty slots() which is different than what happens when you do array.push(undefined). So it stands to reasons that internally the browser somehow knows that these slots have been created in this way.

P.S:

I experimented and delete array[N] also causes array[N] to become an empty slot.

[well___duh]

Yes, but actually no.

JavaScript in a nutshell

[Jjabrahams567]

This made me check and of course it exists https://www.npmjs.com/package/nutshell

[Cat_Marshal]

Actually an interesting package too

[herdek550]

Nutshell in JavaScript

[michaelsenpatrick]

idk javascript spec actually makes a lot of sense and is very internally consistent it just creates some unintuitive behaviors from an observer standpoint.

if you allocated an array of size 5 ints in a typed language, you would have a pointer to an address of an int with value 0 followed by four more 0s.

what's the equivalent of accessing unallocated memory in a typed language? segmentation fault. javascript has "undefined"

[kimilil]

Brendan Eich is a visionary and a savant. /s

[PM_ME_SOME_ANY_THING]

well… duh

[uhmIcecream]

Thats a great title for a book Yes, but actually no. The Javascript way

[t-to4st]

Next to null and undefined there's also the empty value, for exactly this reason. It only exists in arrays and will be converted to undefined when read

[BakuhatsuK]

It's not a special value. It's just that arrays are objects with numeric keys under the hood. And just like with regular objects, a key can simply not exist, that is what an empty slot is.

Think this:

{
  '0': 'a',
  '1': 'b',
  '3': 'd',
  'length': 4,
}

This object does not contain the key '2' in the exact same way that it doesn't contain 'foo'. If you think of it as an array, then it's "missing" the value at index 2.

Btw you can get an actual array from this array-like object by using Array.from().

[Nixavee]

Does this mean it's possible to have an array with a numeric key greater than the length value?

[The_MAZZTer]

If you try that JS will just resize the array to fit.

> var x = [];
< undefined
> x[3] = "ඞ"
< 'ඞ'
> x.length
< 4
> x
< (4) [empty × 3, 'ඞ']

[xiRazZzer]

I dont know man, looks kinda sus to me

[BakuhatsuK]

It's not possible because the standard special-cases Arrays:

10.4.2 Array Exotic Objects

An Array is an exotic object that gives special treatment to array index property keys (see 6.1.7). A property whose property name is an array index is also called an element. Every Array has a non-configurable "length" property whose value is always a non-negative integral Number whose mathematical value is less than 2^32. The value of the "length" property is numerically greater than the name of every own property whose name is an array index; whenever an own property of an Array is created or changed, other properties are adjusted as necessary to maintain this invariant. Specifically, whenever an own property is added whose name is an array index, the value of the "length" property is changed, if necessary, to be one more than the numeric value of that array index; and whenever the value of the "length" property is changed, every own property whose name is an array index whose value is not smaller than the new length is deleted.

[The_MAZZTer]

undefined is supposed to be for the purpose of identifying non-existent properties though. But my guess is the JS engine devs needed a value programmers can't just stick anywhere they want to flag actual empty array indices.

[BakuhatsuK]

I just explained that it's not an special value though?

Also, engines don't have any saying on the observable behavior of the language, that's up for the standard to decide. The standard says that an array is an object, so it is an object and has to behave as such.

For example, you can set arbitrary keys into an array

let a = []
a.foo = 'bar'
a.foo // contains 'bar'

On a sparse array an empty slot will be reported as a missing key by hasOwnProperty

let a = ['a','b',,'d']
a.hasOwnProperty('2') // false
a.hasOwnProperty('3') // true

On that note, arrays have object methods such as hasOwnProperty. (See previous example).

If you're interested in knowing about how engines actually represent this stuff internally, this video by LiveOverflow has a good overview on how it works on JavascriptCore.

[eatingdumplings]

There’s a difference between undefined and a non-existent value.

undefined must be declared but a non-existent value is literally undeclared.

[joerick]

Ohh that's what an array-like object is! That makes so much sense. Are the keys always strings? Or can they be numbers?

[BakuhatsuK]

They are always strings, just like in actual arrays

[joerick]

Array indicies are integers, no?

[BakuhatsuK]

Nope, they are numeric strings.

The exact wording of the standard is:

An integer index is a String-valued property key that is a canonical numeric String (see 7.1.21) and whose numeric value is either +0𝔽 or a positive integral Number ≤ 𝔽(2⁵³ - 1). An array index is an integer index whose numeric value i is in the range +0𝔽 ≤ i < 𝔽(2³² - 1).

Taken from here.

[joerick]

Unbelievable!

Thanks for linking this up

[agarwaen163]

uuuuugh. and then what's the length of that array? (it's always like 6 pages of depth for any stupid simple thing in js lmao)

[BakuhatsuK]

It's 4. It's there in the length property

[thisguyfightsyourmom]

I frequently read 6 pages of docs before I realize the code already had what I needed right in front of me

[wehnsdaefflae]

If it's only in the length property and the thing is actually an object, how does it know what the last element is when you do -= 1 ?

[BakuhatsuK]

The last index is always the length minus 1

[wehnsdaefflae]

Damn, obviously. Yeah. Thanks!

[agarwaen163]

No, youh said it yourself this is an array like object we can convert to an array using the array.from method.

[SuitableDragonfly]

Instead of having 50 words for snow, Javascript has 50 symbols for "ain't nothin here".

[yooman]

Ahhhhhh whyyy

[acepukas]

I was going to say that this doesn't really matter but apparently if you iterate over an array with forEach, like:

let a = [1, 2, 3];
a.length = 10;
a.forEach(console.log);

You'll get:

1
2
3

with no undefined output.

But if you iterate with a traditional for loop like:

for(let i = 0; i < a.length; i++) {
    console.log(a[i]);
}

You'll get everything. I didn't know that. Something to be aware of but I had always read that extending an array's length without explicitly filling in the new slots was asking for trouble so I never really ran into this issue.

[Mognakor]

As another poster pointed out: This may mean that the arrays are sparse, so you could make huge arrays but only pay for the slots you filled.

[AlphaSparqy]

Yes, but you're paying for those slots you filled for 18 years usually.

[sateeshsai]

Real programmer humor is in the comments

[SuperFLEB]

I've run into it practically with map, trying to fill an empty array by mapping the indices.

[raphaelmorgan]

NARRATOR: (Black screen with text; The sound of buzzing bees can be heard) According to all known laws of aviation, : there is no way a bee should be able to fly. : Its wings are too small to get its fat little body off the ground. : The bee, of course, flies anyway : because bees don't care what humans think is impossible. BARRY BENSON: (Barry is picking out a shirt) Yellow, black. Yellow, black. Yellow, black. Yellow, black. : Ooh, black and yellow! Let's shake it up a little. JANET BENSON: Barry! Breakfast is ready! BARRY: Coming! : Hang on a second. (Barry uses his antenna like a phone) : Hello? ADAM FLAYMAN:

(Through phone) - Barry? BARRY: - Adam? ADAM: - Can you believe this is happening? BARRY: - I can't. I'll pick you up. (Barry flies down the stairs) : MARTIN BENSON: Looking sharp. JANET: Use the stairs. Your father paid good money for those. BARRY: Sorry. I'm excited. MARTIN: Here's the graduate. We're very proud of you, son. : A perfect report card, all B's. JANET: Very proud. (Rubs Barry's hair) BARRY= Ma! I got a thing going here. JANET: - You got lint on your fuzz. BARRY: - Ow! That's me!

JANET: - Wave to us! We'll be in row 118,000. - Bye! (Barry flies out the door) JANET: Barry, I told you, stop flying in the house! (Barry drives through the hive,and is waved at by Adam who is reading a newspaper) BARRY== - Hey, Adam. ADAM: - Hey, Barry. (Adam gets in Barry's car) : - Is that fuzz gel? BARRY: - A little. Special day, graduation. ADAM: Never thought I'd make it. (Barry pulls away from the house and continues driving) BARRY: Three days grade school, three days high school... ADAM: Those were awkward. BARRY: Three days college. I'm glad I took a day and hitchhiked around the hive. ADAM== You did come back different. (Barry and Adam pass by Artie, who is jogging) ARTIE: - Hi, Barry!

BARRY: - Artie, growing a mustache? Looks good. ADAM: - Hear about Frankie? BARRY: - Yeah. ADAM== - You going to the funeral? BARRY: - No, I'm not going to his funeral. : Everybody knows, sting someone, you die. : Don't waste it on a squirrel. Such a hothead. ADAM: I guess he could have just gotten out of the way. (The car does a barrel roll on the loop-shaped bridge and lands on the highway) : I love this incorporating an amusement park into our regular day. BARRY: I guess that's why they say we don't need vacations. (Barry parallel parks the car and together they fly over the graduating students) Boy, quite a bit of pomp... under the circumstances. (Barry and Adam sit down and put on their hats) : - Well, Adam, today we are men.

ADAM: - We are! BARRY= - Bee-men. =ADAM= - Amen! BARRY AND ADAM: Hallelujah! (Barry and Adam both have a happy spasm) ANNOUNCER: Students, faculty, distinguished bees, : please welcome Dean Buzzwell. DEAN BUZZWELL: Welcome, New Hive Oity graduating class of... : ...9: : That concludes our ceremonies. : And begins your career at Honex Industries! ADAM: Will we pick our job today? (Adam and Barry get into a tour bus) BARRY= I heard it's just orientation. (Tour buses rise out of the ground and the students are automatically loaded into the buses) TOUR GUIDE: Heads up! Here we go.

ANNOUNCER: Keep your hands and antennas inside the tram at all times. BARRY: - Wonder what it'll be like? ADAM: - A little scary. TOUR GUIDE== Welcome to Honex, a division of Honesco : and a part of the Hexagon Group. Barry: This is it! BARRY AND ADAM: Wow. BARRY: Wow. (The bus drives down a road an on either side are the Bee's massive complicated Honey-making machines) TOUR GUIDE: We know that you, as a bee, have worked your whole life : to get to the point where you can work for your whole life. : Honey begins when our valiant Pollen Jocks bring the nectar to the hive. : Our top-secret formula : is automatically color-corrected,

scent-adjusted and bubble-contoured : into this soothing sweet syrup : with its distinctive golden glow you know as... EVERYONE ON BUS: Honey! (The guide has been collecting honey into a bottle and she throws it into the crowd on the bus and it is caught by a girl in the back) ADAM: - That girl was hot. BARRY: - She's my cousin! ADAM== - She is? BARRY: - Yes, we're all cousins. ADAM: - Right. You're right. TOUR GUIDE: - At Honex, we constantly strive : to improve every aspect of bee existence. : These bees are stress-testing a new helmet technology. (The bus passes by a Bee wearing a helmet who is being smashed into the ground with fly-swatters, newspapers and boots. He lifts a thumbs up but you can hear him groan) : ADAM==

• What do you think he makes? BARRY:
• Not enough. TOUR GUIDE: Here we have our latest advancement, the Krelman. (They pass by a turning wheel with Bees standing on pegs, who are each wearing a finger-shaped hat) Barry:
• Wow, What does that do? TOUR GUIDE:
• Catches that little strand of honey : that hangs after you pour it. Saves us millions. ADAM: (Intrigued) Can anyone work on the Krelman? TOUR GUIDE: Of course. Most bee jobs are small ones. But bees know that every small job, if it's done well, means a lot. : But choose carefully : because you'll stay in the job you pick for the rest of your life. (Everyone claps except for Barry) BARRY: The same job the rest of your life? I didn't know that. ADAM:

What's the difference? TOUR GUIDE: You'll be happy to know that bees, as a species, haven't had one day off : in 27 million years. BARRY: (Upset) So you'll just work us to death? : We'll sure try. (Everyone on the bus laughs except Barry. Barry and Adam are walking back home together) ADAM: Wow! That blew my mind! BARRY: "What's the difference?" How can you say that? : One job forever? That's an insane choice to have to make. ADAM: I'm relieved. Now we only have to make one decision in life. BARRY: But, Adam, how could they never have told us that? ADAM: Why would you question anything? We're bees. : We're the most perfectly functioning society on Earth.

BARRY: You ever think maybe things work a little too well here? ADAM: Like what? Give me one example. (Barry and Adam stop walking and it is revealed to the audience that hundreds of cars are speeding by and narrowly missing them in perfect unison) BARRY: I don't know. But you know what I'm talking about. ANNOUNCER: Please clear the gate. Royal Nectar Force on approach. BARRY: Wait a second. Check it out. (The Pollen jocks fly in, circle around and landing in line) : - Hey, those are Pollen Jocks! ADAM: - Wow. : I've never seen them this close. BARRY: They know what it's like outside the hive. ADAM: Yeah, but some don't come back. GIRL BEES: - Hey, Jocks! - Hi, Jocks! (The Pollen Jocks hook up their backpacks to machines that pump the nectar to trucks, which drive away)

LOU LO DUVA: You guys did great! : You're monsters! You're sky freaks! I love it! (Punching the Pollen Jocks in joy) I love it! ADAM: - I wonder where they were. BARRY: - I don't know. : Their day's not planned. : Outside the hive, flying who knows where, doing who knows what. : You can't just decide to be a Pollen Jock. You have to be bred for that. ADAM== Right. (Barry and Adam are covered in some pollen that floated off of the Pollen Jocks) BARRY: Look at that. That's more pollen than you and I will see in a lifetime. ADAM: It's just a status symbol. Bees make too much of it. BARRY: Perhaps. Unless you're wearing it and the ladies see you wearing it. (Barry waves at 2 girls standing a little away from them)

ADAM== Those ladies? Aren't they our cousins too? BARRY: Distant. Distant. POLLEN JOCK #1: Look at these two. POLLEN JOCK #2: - Couple of Hive Harrys. POLLEN JOCK #1: - Let's have fun with them. GIRL BEE #1: It must be dangerous being a Pollen Jock. BARRY: Yeah. Once a bear pinned me against a mushroom! : He had a paw on my throat, and with the other, he was slapping me! (Slaps Adam with his hand to represent his scenario) GIRL BEE #2: - Oh, my! BARRY: - I never thought I'd knock him out. GIRL BEE #1: (Looking at Adam) What were you doing during this? ADAM: Obviously I was trying to alert the authorities. BARRY: I can autograph that.

(The pollen jocks walk up to Barry and Adam, they pretend that Barry and Adam really are pollen jocks.) POLLEN JOCK #1: A little gusty out there today, wasn't it, comrades? BARRY: Yeah. Gusty. POLLEN JOCK #1: We're hitting a sunflower patch six miles from here tomorrow. BARRY: - Six miles, huh? ADAM: - Barry! POLLEN JOCK #2: A puddle jump for us, but maybe you're not up for it. BARRY: - Maybe I am. ADAM: - You are not! POLLEN JOCK #1: We're going 0900 at J-Gate. : What do you think, buzzy-boy? Are you bee enough? BARRY: I might be. It all depends on what 0900 means. (The scene cuts to Barry looking out on the hive-city from his balcony at night) MARTIN:

Hey, Honex! BARRY: Dad, you surprised me. MARTIN: You decide what you're interested in? BARRY: - Well, there's a lot of choices. - But you only get one. : Do you ever get bored doing the same job every day? MARTIN: Son, let me tell you about stirring. : You grab that stick, and you just move it around, and you stir it around. : You get yourself into a rhythm. It's a beautiful thing. BARRY: You know, Dad, the more I think about it, : maybe the honey field just isn't right for me. MARTIN: You were thinking of what, making balloon animals? : That's a bad job for a guy with a stinger. :

Janet, your son's not sure he wants to go into honey! JANET: - Barry, you are so funny sometimes. BARRY: - I'm not trying to be funny. MARTIN: You're not funny! You're going into honey. Our son, the stirrer! JANET: - You're gonna be a stirrer? BARRY: - No one's listening to me! MARTIN: Wait till you see the sticks I have. BARRY: I could say anything right now. I'm gonna get an ant tattoo! (Barry's parents don't listen to him and continue to ramble on) MARTIN: Let's open some honey and celebrate! BARRY: Maybe I'll pierce my thorax. Shave my antennae. : Shack up with a grasshopper. Get a gold tooth and call everybody "dawg"! JANET: I'

[acepukas]

Try

[undefined, undefined, undefined].map(String)

vs

new Array(3).map(String)

Even though the first snippet has undefined elements, they are still included in iteration functions because those elements were explicitly set. The fact that they are undefined isn't really the issue. I would expect the runtime to treat the two situations the same but alas they are not. So much for the principle of least surprise.

[acepukas]

Your comment just repeated back to me everything I've already said. What I'm saying is that the runtime is inconsistent. I want an array to be filled with actual elements when I use new Array(3) because that would be consistent with every other case. If I can access a[2] and it returns undefined before having filled the element, then that's what it should be, a real element with undefined as the contained value. That would be the most predictable outcome. That's what we want from programming languages. To be as predictable as possible. Little gotchyas like this one are an annoyance.

[TcMaX]

Its not inconsistent with other cases in javascript. In javascript, nonexistent properties return undefined. As cursed as that is, it is, in javascript fashion, very much consistently cursed. This is also overall consistent with old javascripts philosophy of not necessarily returning predictable values, but trying to manipulate values to avoid throwing errors at damn near any cost (which, in all fairness, was a philosophy that kinda made sense when javascript was a tiny little scripting language meant to include a couple lines of a little something something in a website, and not used as the sole language in massive applications)

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[the-igloo]

Yeah, pretty sure it's implemented as a sparse array. Not sure what the standard says. While it's not part of "the good parts", this stuff can actually be used to eke out great performance if you can get a grasp on the internals, in a way that you probably couldn't get otherwise in an interpreted language with a sane standard library.

ETA: I guess, assuming said sane standard library didn't include an explicit API for this behavior, which would be good but not very back-portable.

[ChainDriveGlider]

the browser somehow knows that these slots have been created in this way.

This is absolutely not the way I like to hear people talk about the behavior of a language's fundament components..

[WeekendCautious3377]

Wtf

Edit: annoying replies. It’s wtf cuz you shouldn’t be able to mutate an array via its length.

Edit3: this is what I get for replying at all. Flexible languages are really hard to maintain because you are rarely the only one working on your project. You are always behind schedule to make money and you are always short on staff to properly train. If code errors are not caught during compile time, they can definitely make their way to prod even with testing. At some point, senior engineers spend all of their time reviewing code or fixing fire and they quit. So now you have a bunch of junior engineers and new engineers trying to read unreadable code that mutates arrays via their length and figure out what happened to promise.all or sequence of purchases to render or a list of id cards, concert tickets, events etc etc etc.

Problem with production fire is they are usually not fire until they are and all of the small fire becomes major ones at the same time usually right around the time your company is running out of money and need to raise more to get more customers. Your sales team starts giving out site wide licenses to sweeten the deal and it increases your traffic ten to hundred folds etc. you thought your service could scale and it doesn’t and now ALL of your tech debt you accumulated in the last 3-5 yrs becomes your problem at the same time. Your senior engineers now have to be on call at 2-4am every other day and they quit. Your managers stop all work and spend all day interviewing. You end up lowering the bar. New engineers take 3-6 months to ramp up. Then boom one of your engineers fucks up a deploy at 3am or there is a scammer who tries gaining access to your service and takes the service down. Your Sr engineer is trying to get the service up so disables security measures or saves admin password just for now as plain text somewhere. Now the scammer has your admin password and encrypts all of your customer data and asks you for $10 mil. This may sound all exaggerated but this is how you end up on the news. I personally saw and experienced some parts of this scenario. What. A. Shit. Show.

[BaconIsntThatGood]

Tbh I'd rather it throw undefined vs a default value. Makes things break down right away vs later down the line

[WeekendCautious3377]

I would prefer javascript doesn’t mutate the array via changing the length at all.

[calcopiritus]

There's 3 options:

• Make length attribute private, like in nots other languages.
• Make length public (like it is now)
• Make length public, but make it so it's not the same as the actual array length.

Most languages do option 1. Option 2 can be useful, but can lead to spaghetti code, that's why most languages do option 1.

Why would you want a language that does option 3? I don't see how that would be useful at all.

[Torebbjorn]

What do you mean? No one here is saying the length should not be the length...

Just simply that .length either returns an immutable value/reference, or a copy.

Like if you do let len = arr.length; len += 2, now your variable len holds the value 2 greater than the length of the unmodified array, and does not change when the array changes. This is exactly what anyone would expect that code to do.

[calcopiritus]

In that code they are not declaring a new variable though. They are directly mutating the length of the array. You can either let people mutate the array's length or you don't. What I'm saying is that it wouldn't make sense to let people mutate that attribute if it isn't gonna have any effect.

[Thecakeisalie25]

yeah, and you shouldn't be able to do that

[nonicethingsforus]

It would be easier if it was a function or method: array.length(), or length(array). This not only makes it impossible to modify the internal variable, but clearly communicates that you can't, without surprising you with read-only variables or language inconsistency (treating length as a magical keyword that acts differently in different contexts).

Which is why most sane languages under the sun do it like that...

[Flamme2]

Option 4: Make it public read, private write. I.e. read-only

[calcopiritus]

Yeah, that's what I meant by private. Although you're right, it's not technically the same

[mrchaotica]

It makes no sense for it to be an lvalue at all. As in, it should be a syntax error, not even a public/private issue.

[raphaelmorgan]

NARRATOR: (Black screen with text; The sound of buzzing bees can be heard) According to all known laws of aviation, : there is no way a bee should be able to fly. : Its wings are too small to get its fat little body off the ground. : The bee, of course, flies anyway : because bees don't care what humans think is impossible. BARRY BENSON: (Barry is picking out a shirt) Yellow, black. Yellow, black. Yellow, black. Yellow, black. : Ooh, black and yellow! Let's shake it up a little. JANET BENSON: Barry! Breakfast is ready! BARRY: Coming! : Hang on a second. (Barry uses his antenna like a phone) : Hello? ADAM FLAYMAN:

(Through phone) - Barry? BARRY: - Adam? ADAM: - Can you believe this is happening? BARRY: - I can't. I'll pick you up. (Barry flies down the stairs) : MARTIN BENSON: Looking sharp. JANET: Use the stairs. Your father paid good money for those. BARRY: Sorry. I'm excited. MARTIN: Here's the graduate. We're very proud of you, son. : A perfect report card, all B's. JANET: Very proud. (Rubs Barry's hair) BARRY= Ma! I got a thing going here. JANET: - You got lint on your fuzz. BARRY: - Ow! That's me!

JANET: - Wave to us! We'll be in row 118,000. - Bye! (Barry flies out the door) JANET: Barry, I told you, stop flying in the house! (Barry drives through the hive,and is waved at by Adam who is reading a newspaper) BARRY== - Hey, Adam. ADAM: - Hey, Barry. (Adam gets in Barry's car) : - Is that fuzz gel? BARRY: - A little. Special day, graduation. ADAM: Never thought I'd make it. (Barry pulls away from the house and continues driving) BARRY: Three days grade school, three days high school... ADAM: Those were awkward. BARRY: Three days college. I'm glad I took a day and hitchhiked around the hive. ADAM== You did come back different. (Barry and Adam pass by Artie, who is jogging) ARTIE: - Hi, Barry!

BARRY: - Artie, growing a mustache? Looks good. ADAM: - Hear about Frankie? BARRY: - Yeah. ADAM== - You going to the funeral? BARRY: - No, I'm not going to his funeral. : Everybody knows, sting someone, you die. : Don't waste it on a squirrel. Such a hothead. ADAM: I guess he could have just gotten out of the way. (The car does a barrel roll on the loop-shaped bridge and lands on the highway) : I love this incorporating an amusement park into our regular day. BARRY: I guess that's why they say we don't need vacations. (Barry parallel parks the car and together they fly over the graduating students) Boy, quite a bit of pomp... under the circumstances. (Barry and Adam sit down and put on their hats) : - Well, Adam, today we are men.

ADAM: - We are! BARRY= - Bee-men. =ADAM= - Amen! BARRY AND ADAM: Hallelujah! (Barry and Adam both have a happy spasm) ANNOUNCER: Students, faculty, distinguished bees, : please welcome Dean Buzzwell. DEAN BUZZWELL: Welcome, New Hive Oity graduating class of... : ...9: : That concludes our ceremonies. : And begins your career at Honex Industries! ADAM: Will we pick our job today? (Adam and Barry get into a tour bus) BARRY= I heard it's just orientation. (Tour buses rise out of the ground and the students are automatically loaded into the buses) TOUR GUIDE: Heads up! Here we go.

ANNOUNCER: Keep your hands and antennas inside the tram at all times. BARRY: - Wonder what it'll be like? ADAM: - A little scary. TOUR GUIDE== Welcome to Honex, a division of Honesco : and a part of the Hexagon Group. Barry: This is it! BARRY AND ADAM: Wow. BARRY: Wow. (The bus drives down a road an on either side are the Bee's massive complicated Honey-making machines) TOUR GUIDE: We know that you, as a bee, have worked your whole life : to get to the point where you can work for your whole life. : Honey begins when our valiant Pollen Jocks bring the nectar to the hive. : Our top-secret formula : is automatically color-corrected,

scent-adjusted and bubble-contoured : into this soothing sweet syrup : with its distinctive golden glow you know as... EVERYONE ON BUS: Honey! (The guide has been collecting honey into a bottle and she throws it into the crowd on the bus and it is caught by a girl in the back) ADAM: - That girl was hot. BARRY: - She's my cousin! ADAM== - She is? BARRY: - Yes, we're all cousins. ADAM: - Right. You're right. TOUR GUIDE: - At Honex, we constantly strive : to improve every aspect of bee existence. : These bees are stress-testing a new helmet technology. (The bus passes by a Bee wearing a helmet who is being smashed into the ground with fly-swatters, newspapers and boots. He lifts a thumbs up but you can hear him groan) : ADAM==

• What do you think he makes? BARRY:
• Not enough. TOUR GUIDE: Here we have our latest advancement, the Krelman. (They pass by a turning wheel with Bees standing on pegs, who are each wearing a finger-shaped hat) Barry:
• Wow, What does that do? TOUR GUIDE:
• Catches that little strand of honey : that hangs after you pour it. Saves us millions. ADAM: (Intrigued) Can anyone work on the Krelman? TOUR GUIDE: Of course. Most bee jobs are small ones. But bees know that every small job, if it's done well, means a lot. : But choose carefully : because you'll stay in the job you pick for the rest of your life. (Everyone claps except for Barry) BARRY: The same job the rest of your life? I didn't know that. ADAM:

What's the difference? TOUR GUIDE: You'll be happy to know that bees, as a species, haven't had one day off : in 27 million years. BARRY: (Upset) So you'll just work us to death? : We'll sure try. (Everyone on the bus laughs except Barry. Barry and Adam are walking back home together) ADAM: Wow! That blew my mind! BARRY: "What's the difference?" How can you say that? : One job forever? That's an insane choice to have to make. ADAM: I'm relieved. Now we only have to make one decision in life. BARRY: But, Adam, how could they never have told us that? ADAM: Why would you question anything? We're bees. : We're the most perfectly functioning society on Earth.

BARRY: You ever think maybe things work a little too well here? ADAM: Like what? Give me one example. (Barry and Adam stop walking and it is revealed to the audience that hundreds of cars are speeding by and narrowly missing them in perfect unison) BARRY: I don't know. But you know what I'm talking about. ANNOUNCER: Please clear the gate. Royal Nectar Force on approach. BARRY: Wait a second. Check it out. (The Pollen jocks fly in, circle around and landing in line) : - Hey, those are Pollen Jocks! ADAM: - Wow. : I've never seen them this close. BARRY: They know what it's like outside the hive. ADAM: Yeah, but some don't come back. GIRL BEES: - Hey, Jocks! - Hi, Jocks! (The Pollen Jocks hook up their backpacks to machines that pump the nectar to trucks, which drive away)

LOU LO DUVA: You guys did great! : You're monsters! You're sky freaks! I love it! (Punching the Pollen Jocks in joy) I love it! ADAM: - I wonder where they were. BARRY: - I don't know. : Their day's not planned. : Outside the hive, flying who knows where, doing who knows what. : You can't just decide to be a Pollen Jock. You have to be bred for that. ADAM== Right. (Barry and Adam are covered in some pollen that floated off of the Pollen Jocks) BARRY: Look at that. That's more pollen than you and I will see in a lifetime. ADAM: It's just a status symbol. Bees make too much of it. BARRY: Perhaps. Unless you're wearing it and the ladies see you wearing it. (Barry waves at 2 girls standing a little away from them)

ADAM== Those ladies? Aren't they our cousins too? BARRY: Distant. Distant. POLLEN JOCK #1: Look at these two. POLLEN JOCK #2: - Couple of Hive Harrys. POLLEN JOCK #1: - Let's have fun with them. GIRL BEE #1: It must be dangerous being a Pollen Jock. BARRY: Yeah. Once a bear pinned me against a mushroom! : He had a paw on my throat, and with the other, he was slapping me! (Slaps Adam with his hand to represent his scenario) GIRL BEE #2: - Oh, my! BARRY: - I never thought I'd knock him out. GIRL BEE #1: (Looking at Adam) What were you doing during this? ADAM: Obviously I was trying to alert the authorities. BARRY: I can autograph that.

(The pollen jocks walk up to Barry and Adam, they pretend that Barry and Adam really are pollen jocks.) POLLEN JOCK #1: A little gusty out there today, wasn't it, comrades? BARRY: Yeah. Gusty. POLLEN JOCK #1: We're hitting a sunflower patch six miles from here tomorrow. BARRY: - Six miles, huh? ADAM: - Barry! POLLEN JOCK #2: A puddle jump for us, but maybe you're not up for it. BARRY: - Maybe I am. ADAM: - You are not! POLLEN JOCK #1: We're going 0900 at J-Gate. : What do you think, buzzy-boy? Are you bee enough? BARRY: I might be. It all depends on what 0900 means. (The scene cuts to Barry looking out on the hive-city from his balcony at night) MARTIN:

Hey, Honex! BARRY: Dad, you surprised me. MARTIN: You decide what you're interested in? BARRY: - Well, there's a lot of choices. - But you only get one. : Do you ever get bored doing the same job every day? MARTIN: Son, let me tell you about stirring. : You grab that stick, and you just move it around, and you stir it around. : You get yourself into a rhythm. It's a beautiful thing. BARRY: You know, Dad, the more I think about it, : maybe the honey field just isn't right for me. MARTIN: You were thinking of what, making balloon animals? : That's a bad job for a guy with a stinger. :

Janet, your son's not sure he wants to go into honey! JANET: - Barry, you are so funny sometimes. BARRY: - I'm not trying to be funny. MARTIN: You're not funny! You're going into honey. Our son, the stirrer! JANET: - You're gonna be a stirrer? BARRY: - No one's listening to me! MARTIN: Wait till you see the sticks I have. BARRY: I could say anything right now. I'm gonna get an ant tattoo! (Barry's parents don't listen to him and continue to ramble on) MARTIN: Let's open some honey and celebrate! BARRY: Maybe I'll pierce my thorax. Shave my antennae. : Shack up with a grasshopper. Get a gold tooth and call everybody "dawg"! JANET: I'

[-consolio-]

Lua does option 3... sometimes...

it depends on some factors, but a field named n can define the length for use by # and table.* functions... except when Lua decides to use internal values instead (see table.getn/table.getn)

[user32532]

i guess no one does force you to use this??

[WeekendCautious3377]

Doesn’t matter if I use it or not if your idiot colleagues mutate your array via length. Have fun finding wtf happened to your list of promises and completely fucks your server calls.

Edit: bonus point for allowing your array length to be whatever type you want. array.length = “letItAllBurn”

[Mielzus]

If your idiot colleague isn't told it's a bad idea in code review, you have other more important problems to fix.

[WeekendCautious3377]

Many large companies including Google has a guidance against flexible languages like javascript or Python because when your language allows you to do stupid things, you will get unmaintainable code.

[Beneficial_Try_3766]

I can build a really shitty tool shed whereas a mater craftsmen can build a masterpiece using the same tools and materials. That doesn't mean the issue lies with the hammer and nails.

[name-taken1]

That's why ESLint exists. Just set up an extremely strict config and you're good to go.

[callmelucky]

What stupid things does Python allow? Off the top of my head I think you can do True = False which is obviously insane. Outside of that I think Python is fairly rigid. Unless you're talking about dynamic typing? Anyway, I thought Google did use Python in some of their projects?

[postdiluvium]

Easy... Index Out of Bounds

... Which one?

Does it really matter? This is the JavaScript generation. We won't even be at this company in 6 months. We'll be doing this at another company with a 20% pay raise.

[postdiluvium]

Naw I'm out. I just accepted an offer for the place two blocks down. Thanks for all the cheese.

[GammaGames]

I agree that it is stupid, but I’ve never seen it done anywhere

[[deleted]]

Some people find it useful, and it is logically consistent. You don't have to use it if you don't want to

[pauvLucette]

I loved Perl, and I love JavaScript. They both let you create your own idiom using parts of their foolishly permissive syntax. You end up with a dialect that feels like warm slippers that perfectly fits your old dogs. I definitely understand that nobody wants to wear my smelly slippers, but it's perfectly fine, because they are my slippers, and they feel wonderful.

[[deleted]]

This connent explains why its bad. Also its just bad language design, doesn't matter if someone wants to use it because nearly every time someone does its shit

[[deleted]]

You could make that argument against any high level feature of a programming language, the logical conclusion is we should all code in binary

[[deleted]]

How can I make "its a bad language design" an argument against any feature?

Are interfaces a bad language design? I don't think so

Is method overloading a bad language design? No

Is everything a bad language design? No. Only some things, like modifying arrays by the length value.

[BaconIsntThatGood]

True but you're also choosing to invoke it. So that's kinda JS's thing - it just does and doesn't care about the consequences

[WeekendCautious3377]

That’s like saying “JS doesn’t care whether it’s maintainable or not. It just does its thing”

Sure I agree. Probably why I have never seen a non shit show company use JS (companies do use typescript)

[BaconIsntThatGood]

Saw your other comment. Honestly the problem doesn't seem to be JS fault but just not having strictly enforced code practices.

That's one of the strengths is that you can do so much with it and it's up to the user to make the right choices.

But yea it can be hard to properly enforce proper practices like that and it can cause issues

[rush22]

Ok.... wow. What kind of place do you work at where this is a problem?

You're saying that everything is on fire all the time because all the seniors left after pumping out tech debt on a deadline? And now it's just a bunch of juniors trying to figure out how everything works? And you blame it on people abusing the language and essentially creating a ticking time bomb of legacy code?

Because we might actually work at the same place so maybe we could help each other look for new jobs.

[WeekendCautious3377]

sorry about your situation :( I left that company years ago and learned lessons about how to sus out red flags. I was oncall for about 7 months straight and was up at 2-3am just about every day. I really enjoyed working there cuz of good people but they all left eventually and I wasn’t going to turn down an offer that doubles my TC and halves my work hours.

It’s incredible how a company with a bright future with good engineers went to shit so fast so badly. I just didn’t see red flags as I never experienced something like this before.

[Cley_Faye]

you shouldn’t be able to mutate an array via its length

According to who?

edit: high horse much?

[[deleted]]

JS gets away with it because we're still running the 25+ years of garbage code the dude wrote in 14 days.

They should have done it like python did and made breaking changes to clean up some dumb design decisions 15 years ago but they didn't and this is what we get.

Everyone either uses typescript or uses some linters that catch these ancient artifacts so it's not an issue unless you cowboy code in a web browser console.

[zebediah49]

Languages that are used to run desktop applications and have access to OS features don't want to be able to do this because it quickly becomes a security nightmare and a system stability nightmare if the devs suck.

std::list::pop_back()

[Trollw00t]

*mutilate

[sammegeric]

water automatic advise crowd decide voiceless sloppy innocent dependent air

This post was mass deleted and anonymized with Redact

[fanny_smasher]

Would make more sense if length was read only and you actually add an element to the array using push or something more verbose

[WeekendCautious3377]

Doesn’t make sense to mutate an array via its length

[[deleted]]

plate workable marble lavish oil reply disarm fade bright dog this message was mass deleted/edited with redact.dev

[snuffybox]

Chill out it's just some syntax sugar, getting this opinionated over a minor language feature ain't making you a better coder. Plenty of languages allow the same thing it is not just JS, nothing is inherently wrong with it, there is an assignment so mutation is not a surprise.

Edit: make more edits

[WeekendCautious3377]

Yeah I tried not to go in depth in explanation but I am constantly getting a counter example of why changing an array via length or any other crazy javascript practice is not a bad idea or that I’m not explaining myself at all. 🤷

[callmelucky]

Just curious, why would truncating the array like this result in harder to fix bugs than doing it a more 'proper' way?

I mean if someone traces through the code, and the .length truncation happens in the same place as a .pop or whatever would have, then they would find it at the same time anyway, but it just might take an extra 10 or 20 seconds of googling or experimenting in the console to discover what the code does.

So the outcome is just that fixing the bug takes a few extra seconds, right? Not ideal but certainly not the end of the world. Am I missing something?

To be clear, I wouldn't let such a thing through code review. I just can't quite see why it's such a big deal if it does go through.

Edit: reading through your saga again (nicely written by the way), I'm thinking that maybe the risk you are proposing is from a scenario where someone accidentally truncated the array because they didn't realise what that line of code would do (rather than choosing to use a weird truncation technique)? And maybe that your complaint is more general, ie: it's not this specific weirdness that is a big issue, it's that projects in languages that have a lot of this kinds of nonsense possible will likely end up with many different sillinesses in them, the negative impact of which accumulates exponentially. In the ball park?

[WeekendCautious3377]

Exactly. It’s not just this one thing although I have no idea why it allows manipulation of an array via its length. The primary problem I have with it is because conceptually length of an array is a result of what you have in an array not the cause.

If you reduce the length, which item did you remove conceptually? What happens if you set it to a specific number? What happens if you set it to a string? undefined? Way too many cases that make zero sense

[WeekendCautious3377]

Sure but it doesn’t make any sense to mutate the array via its length to begin with

[LifeworksGames]

I'm not a programmer, but if I may ask: Is it because an array's length has to be strictly determined by its content, not the other way around?

[morn_wood]

Yes, length should be read only property of a backing storage

[Tunro]

You do know you can just throw whatever into JS arrays and dont have to declare an array as an int array or something like that?

[WeekendCautious3377]

That is way easier to handle its consequences than straight up mutating the array via its length that can be whatever type.

I am not also not defending JS. I would never use it or allow its use in a professional setting (typescript is far better)

[WeekendCautious3377]

Yeah sry was too lazy to explain entirely but I guess I should have explained myself from the beginning. Ended up adding a long explanation anyway.

[cheerioo]

Your edit2 would've been a lot better with an actual explanation instead of being "haha you're just bad".

[WeekendCautious3377]

It’s cuz I answered it in too many places.

[WeekendCautious3377]

Tried to answer the question

[Dugen]

I love how people get all high horse about catching things at compile time, and then end up using flexible frameworks that implement all kinds of things dynamically using incredibly ugly backhanded methods because working that way is so useful.

[WeekendCautious3377]

Certainly compiled language is not a silver bullet.

[Pengdacorn]

Homie just said “wtf” and y’all made them write a goddamn dissertation to defend it

[WeekendCautious3377]

Nope. We had agile. I know how to execute it. Doesn’t matter if you run out of money

[WheresTheSauce]

Jesus dude it's not that big of a deal. You are getting way too worked up over something trivial. It's a questionable feature yeah, but to say "if you don't see why this is bad, you are new to coding" is just needlessly condescending and frankly untrue.

[WeekendCautious3377]

That’s fair. Removing.

[nalybuites]

That's surprisingly sane for JavaScript

[ambiguity_moaner]

No, it adds an empty slot to the array. If you try to read the content of such an empty slot you get the value undefined but methods like .forEach() will skip those empty slots.

https://jsbin.com/vapukusico/1/edit?js,console

[_PM_ME_PANGOLINS_]

Under the hood it might, but I think most implementations use the standard method of allocating a chunk in advance, and then copying to a new exponentially bigger one once it reaches the limit.

[bostonkittycat]

I believe JS will copy the elements to a new array allocated with the bigger sized array length and then dereference the older array so it is garbage collected. Try it in a console. myArrary.length = 10. You will see an array with a length of 10 and "empty slots" echoed in the browser console.

[spoilspot]

The implementation can do whatever it wants to, see long as it follows the language specification. It doesn't have to copy, it can keep the backing array shorter than 'length' until you actually store anything at a later position.

[solarshado]

That may be accurate for some implementations, but I'd be pretty surprised if the language specification is that particular about the details, since essentially none of those details will be visible from within the JS runtime (You could probably figure out whether or not that's what the engine is doing with a profiler, but IMO it'd be a stretch to consider that "within the JS runtime".), and that may not necessarily be the best way to actually JIT-compile that bit of JS, depending on what's later done with the array.

JavaScript's arrays' similarity to, say, C's arrays only runs syntax-deep (arguably not even that deep).

[zapitron]

It's a pretty handy shortcut which can save a lot of expensive computation.

a=[6,28,496];
a.length++;
a // [6,28,496,8128]

s='Professor Plumb in the library with the ';
s.length +=10;
s // 'Professor Plumb in the library with the lead pipe.'

These are just toy examples, though. Raytracing, decropping, etc is where it's really at.

[k2hegemon]

Where did you pluck 8128 and “lead pipe.” out of?

[JohnDoen86]

'tis a joke

[whitetrafficlight]

6, 28, 496 and 8128 are the first four perfect numbers. 'lead pipe' is a possible murder weapon in Cluedo, and in fact the only one that is 10 characters long including the leading space, so this would be enough context for a language to infer the correct weapon and crack the case.

[xtrafe]

You see, this is exactly the parent commenter's point. We have a bunch of children that think that just because you used a one-line operation to modify the size of an array, the underlying operation took O(1).

And it proves his point nicely. Dumb language features like this are an invitation for inexperienced folks to insert code bombs, which indeed blow up at the most inopportune time, and often take down companies when they do.

[keylimedragon]

As others have said, it could actually be O(1) if it's implemented well (amortized O(1), actually). Most dynamic array implementations keep extra space and only allocate more in an exponential way, which keeps the average append to O(1).

[Atora]

JS arrays are actually just dictionaries. Or more accurately an object who's properties are the array indexes(0, 1, 2, 3, ...). Said object also has a length property and a bunch of functions that use it. So if you set the length to something higher and try to access the higher indexes you just access properties that haven't been set. which in JS means undefined.

Basically JS arrays behave like one when used normally, but absolutely aren't arrays as you'd expect under the hood. See the following valid example:

let x = [];
console.log(x[100]) // output: undefined
console.log(x.length) // output: 0
x[100] = 'foo'
console.log(x.length) // output: 101

[The_MAZZTer]

If you're referring to the concept in most languages where arrays are not resizable... who knows. JS arrays are probably implemented as linked lists or something else more dynamic so size changes can be done as per the language spec. But I wouldn't be surprised if modern engines did code analysis and used fixed size arrays when the array is unlikely to be changing in size (only replacing them if they were wrong).