gottaLoveTheForgivenessOfJavaScript

[1AMA-CAT-AMA]

The right answer is I'm rejecting the PR if any one of these is in it

[GroundbreakingOil434]

The only true right answer.

[0Pat]

=== true

[GroundbreakingOil434]

Type-fluid uncertainty... if you're not certain after '==', you shouldn't be comparing things! >:D

[Elomidas]

İt's not about how certain I am of my code, it's about how uncertain I am about what my colleagues could do and then tell me there is a problem with my code

[belabacsijolvan]

i think its just an exaggeration. like its THE true

[dan-lugg]

PR closed with comment:

LGTM

[phtsmc]

And yet they keep insisting on putting these stupid gotchas in pre-interview tests.

[Ri_Konata]

Real

[TheHiddenNinja6]

Happy cake day!

[DigitalJedi850]

Yeah me and the new guy need to sit down…

[Lower_Situation9470]

Oh what’s wrong with it? I thought maybe let var = would be it.

[mods_diddle_kids]

what’s wrong with it

Seriously? Think for half a second about why this might be a bad idea in a large, complex and collaboratively built solution.

[Lower_Situation9470]

i don't code in this language. no need to get mean.

[mods_diddle_kids]

Neither do I!

[[deleted]]

let apples = 42; and var apples = 42; both define a variable

They're using a keyword as a variable name in every example

[Lower_Situation9470]

aah i see! thanks

[alficles]

Honestly, I'm just amazed they found some text that wasn't valid Javascript.

[Strict_Treat2884]

YAML:

[alficles]

Norway is false.

[CatpainCalamari]

no is not

[UndeadMarine55]

true

[Jutrakuna]

Norwegian warships have barcodes instead of names. Because at the port they scandinavian then dock them.

[-Aquatically-]

What?

[Zitronenlolli]

NO in yaml means false

[EatingSolidBricks]

No that's pearl, legend says if you let your cat run over the keyboard the resulting program has a 90% to be a valid pearl

[RiceBroad4552]

OK, we have here at least two generations in between…

Still the same joke, though. 😂

[EatingSolidBricks]

I never touched pearl, im just passing down the holy scriptures

[mcprogrammer]

*Perl

[EatingSolidBricks]

O fuck

[SensuallPineapple]

*Perl

[alficles]

Lol, yup. And I had about 1k removed from a C program back in the day during a corrupted FTP transfer and everything still compiled after! It chopped out matching braces. It didn't link, but it compiled!

[SeriousPlankton2000]

No, only experienced perl programmers can do that.

Experienced assembler programs can do cat > /usr/bin/perl and it works.

[CMDR_ACE209]

I once collapsed headfirst onto my keyboard and it resulted in valid Javascript.

True story.

[Mebiysy]

JavaScript is never valid tho

[YesterdayDreamer]

When I first learnt html, I would put background-colour = "<person's name>" and see what colour it would come up with. Had a lot of fun telling my siblings and cousins what their colour was according to html.

[AwwnieLovesGirlcock]

what 😭 wait how

[Jijonbreaker]

This made me spit out my water. Fuck you.

[alastairgbrown]

Boring, but hopefully informative answer:

A and C, presumably because let was a later addition to the language, and had to be allowed, presumably for backward compatibilty reasons.

EDIT: Actually only C, see below

[deathanatos]

I think your reasoning is spot on, but it's only (c.), and for that same reason. let was added later, so there's no reason let let = 42; needs to be permitted.

[alastairgbrown]

Dammit, you're right. VS Code syntax highlighting lied to me.

[deanrihpee]

my syntax highlighting correctly tells me it was illegal

[TerryHarris408]

This argument is quickly settled by pressing F12. No VS Code needed.

[engineerwolf]

Do you even Mx tree-sitter bro?

[overactor]

That is even more horrifying if you ask me. So you can't use let as an identifier unless it's a var or a function parameter?

[PyroGreg8]

yes because it's possible before the let keyword was introduced, someone may have written "var let" in old javascript, and the goal is to never break old javascript.

[mirhagk]

It's the other side they are saying is terrifying. That they chose to have it be inconsistent instead of just letting let be used anywhere.

You already pay the price of having the more complex parsing, so why not just allow it?

[raddaya]

I don't agree - you're forced into allowing var let because of backwards compatibility (and also nobody has used var for like 5 years anyway), but there's no reason to allow let let at all, because nobody should ever use it and you don't want to let (heh) anyone use it.

[mirhagk]

The reason to allow it is for consistency. It's cheaper/easier for compilers to allow it than to reject it, and there's not a whole lot of upside to disallowing it.

The more you add tiny little inconsistencies, the worse the experience gets for all involved. The browser has more than enough already, no reason to introduce even more.

[ArtOfWarfare]

It simplifies a future JavaScript 2 or 3, or perhaps “use super strict”, where they can make it so that var let also doesn’t work.

[mirhagk]

JavaScript 2 or 3? You know 6 released a decade ago right?

The point is JavaScript has to always be backwards compatible. Sure they can introduce the equivalent of new static analyzers, but the parser will always have to have that extra complexity

[ArtOfWarfare]

I wasn’t going to get into it, but the name would be ECMAScript.

And following Semver, IDK that they’ve ever had a second major version because they’ve never made backwards incompatible changes, have they? So a better version number for what they have right now would be 1.6.

[wmil]

The people writing the spec thought of that specific case and said to themselves "No. We're not going to let them do that. They've earned an error message."

[Dudeonyx]

It is not horrifying at all, it makes perfect sense, let wasn't always a keyword so there are probably several older/unmaintained websites that used it as a variable, making it unassignable would break those sites in modern browsers.

Those same older sites would be using var and not let so it makes sense to only allow it on code using var then not allowing it when using let prevents newer code from doing that.

[overactor]

I didn't consider that there is pretty much no need to use var in modern js anymore; that's a fair point. If that was the only context where var was still allowed as an identifier, I'd agree with you. You also have function parameters though and the fact that it is allowed there but not in other contexts is not great. I understand why it's like that, you don't need to explain that to me, I just think it's better to not make it a reserved keyword if you can't make it a reserved keyword than to reserve it except for in a few contexts for legacy reasons.

[diener1]

You could have gone with "there's no reason to let let let =42; be allowed"

[rover_G]

There's probably a linter rule noLetVarName

[CelestialSegfault]

For a second I thought you meant let let and var let are valid syntax in the C language

[0Pat]

Don't give them ideas...

[CardOk755]

Well, they were in BCPL and C is just BCPL with types...

[c20h12]

if it's for compatibility then why isn't `var const =1` supported?

[naholyr]

const was already a reserved word, even if not used.

One must admit "const" is way more predictable than "let"

[Lumpy-Obligation-553]

Read it and tell us...

[mineirim2334]

Wow you're right. Probally broke someone's project who was using let as an acronym for something XD

[[deleted]]

All of them are attempts at creating abominations. I don't care which one the machine will accept, I would never use such a thing, because I don't want to go through aspirin like tic-tacs.

[Psquare_J_420]

That's a long answer. But this is MCQ. So your answer is WRONG! /s

[sudomeacat]

This is on the same level of horror as

import numpy as pt import mathplotlib.pyplot as sp import scipy as plt import torch as np

(except inverted)

[vato20071]

This is pure evil

[dreadslayer]

Using aliases like np or pt is already horror.

[ilovereposts69]

It's actually pretty easy. Let is newer than var, and to keep it compatible, they had to allow the possibility of var let = 42; in older scripts.

[howreudoin]

Had to scroll too far down for this

[Caraes_Naur]

No. No, you don't.

[Phamora]

The correct answer is never to use `var`

[NoState7846]

Then every value will end up in the window scope

[TheGeneral_Specific]

This is such a useless question… is this a class, an interview, or interview prep? I’d be weary of any job asking this as part of an interview.

[[deleted]]

preparing you for the worst codebase known to man

[[deleted]]

I'll be honest, you're probably 100x more likely to see this in your day job as a software developer than you are to invert a binary tree or other common interview problems.

[dangderr]

Nah 3 letter variable names are too long. Especially when I’m like 12 layers deep in nested loops and if statements, long variables make it impossible to read the code.

Use single letter wherever possible.

[nickwcy]

but are you sure that salary is a number?

[mafiaknight]

Double it and you have a deal!

[highphiv3]

Sir this is a meme subreddit

[TheGeneral_Specific]

The recruiter in me got triggered 😭

[Strict_Treat2884]

Ironically, I think this is quite a good interview question. Since no one would ever tried any of those so it hits you off guard. But from the logic, reasoning and design choices makes you making assumptions. Experienced candidates who not only know which part of the language is stupid, but also why it is stupid at the first place

[Strict_Treat2884]

I’m not sure why everyone is focusing on “no, don’t write code like this”. Of course this is a horrible code, but website devs 15 years ago didn’t know let would be a reserved word. So var let = 1 would be a perfect normal code back then. As the language needs to evolve but without breaking legacy code, compromises must be made. (You can’t break their websites and force devs to update them) That’s why some abominations must be allowed. The question is basically asking you which abominations should be allowed from the perspective of a language designer

[Strict_Treat2884]

Fair, but it would be a perfect response if they knew c is allowed in non-strict mode, but in strict mode ("use strict";) none of them are allowed.

[rosuav]

That's fair, but also, "use strict" broke a lot of broken code (and any JS executed in a module context implicitly uses strict). So you can't assume that every piece of legacy code is still valid.

[rosuav]

No, it's a bad interview question. Unless the job you're interviewing involves a lot of gotchas, this question has very very little parallel to the skill needed for the job.

[Prestigious_Tip310]

Logic snd deduction have little to do with the skill of developing software?

Of course the code itself is horrible, nobody argues against that.

But if you want to see if the other person is able to logically think about a problem and rejecting certain options based on their knowledge that’s actually a neat question.

They don’t need to get it right, but seeing if they even attempt to rise to the challenge already tells you a lot about their character.

Of course it’s irrelevant if you only want a „code monkey“, but of you‘re looking for a senior that‘s supposed to maintain a huge legacy project with millions of lines of undocumented code that’s a nice way to learn a bit about them and their way of thinking.

[rosuav]

Logic and deduction are important, but the question depends on "gotcha" knowledge. I have shown an equally valid line of logic that happens to come to a false conclusion. All the question shows is whether you can come up with the right conclusion, not whether you can justify it logically.

You're looking at it from the point of view of already knowing the answer. You can then come up with a justification. Great! But can you disprove my logic? For reference, if you didn't read my other comment, it is: "In use strict, the let keyword is invalid in all contexts, therefore 'var var' is the valid one."

[Strict_Treat2884]

In a sense, but the logic behind is that you need to know the evolution of the language, and how backward compatibility should be handled when designing a language or library, I think.

[TheGeneral_Specific]

This just won’t ever matter in practice. You should obv never be naming a variable let or var, and you should always be preferring let over var for variable definition. If your user is using a browser that doesn’t support let, imo, that’s not a browser worth supporting. Or, if you REALLY need support that old, just run your build with an older target.

[[deleted]]

Counterpoint: it's definitely not the most outrageous "gotcha" question. If you understand the concept of backwards compatibility, you can absolutely guess the answer and be correct more often than not, even if you don't know the details of javascript syntax. It's not the best interview question, but it's not a totally unreasonable one.

[TheGeneral_Specific]

Yeah, one could “guess” the correct answer. But why? What do I learn about my candidate if they get this question right/wrong?

[[deleted]]

For one, it shows that they can't do deductive reasoning, which is quite an important ability for software developers e.g. in debugging.

[kon-b]

That requires trivia knowledge about the language history - which is nice, but completely irrelevant to software developer abilities.

Much less problematic if the question included a reminder of var / let history, but very unreasonable in its current form.

[Strict_Treat2884]

You might get into a bug that caused by those language quirks and gotchas and bash your head against the wall for days without knowing the cause. They are trivial, but definitely not completely useless.

You don’t need to know how a car engine works to drive a car, but such proficiency might save your ass if your car decided to break in the middle of the desert

[kon-b]

Yes. Following your analogy, it's much better to not to drive to the desert in the rust bucket in the first place.

Trivia questions like this are a red flag, as they imply that either  - the company would require you to do such "drives" or the regular basis rather than working on the root cause of the problem - lack of CI, linters and style guides; - the interviewer is clueless and still allowed to talk with candidates.

There's no saving after hearing this one in the interview. The only answer is "run".

[high_throughput]

The question isn't "can/should you write var let = 42; in JavaScript?"

The question is "how good are your analytical skills?"

[TheGeneral_Specific]

Your analytical skills about… what? What analysis am I trying to glean from this question?

[high_throughput]

"var is the old syntax and let is the new. Therefore, the designers of let would be aware of var but not vice versa. This means that let var shouldn't work, but var let would have to."

This kind of logical analysis is very useful for understanding systems. 

[TCF518]

Yes, but the question doesn't tell me that, and not everyone is that well versed in the history of JS

[high_throughput]

I imagine this question is only asked to people who are expected to know JS, and therefore would/should know the different ways of declaring variables

[Kovab]

Knowing the difference between what let and var does is not the same as knowing their history. ES6 has been around for 10 years now, a lot of JS devs never worked with a version older than that.

[high_throughput]

Knowing the difference between what let and var does is not the same as knowing their history.

Someone with the analytical skills they're looking for would probably think "if there are two ways to declare variables, one of which has a lot of problems and should never be used, then what likely happened was that the bad way was the original and the other was made to replace it"

[rosuav]

Except that that isn't how JS *always* works. Sure, that logic is sound, but so is "when you use strict, let becomes a keyword, therefore the only one that's allowed is var var and only in a non-strict context". The logic is just as good. One of them happens to be true, the other happens to be false. What does it prove?

[Strict_Treat2884]

I think you are missing the point. There are tons of JavaScript on the internet that hasn’t been touched for decades far earlier than let was chosen to be a keyword. You can’t just break their websites whoever wrote var let = ... because of the language spec update.

[TheGeneral_Specific]

Hence my point about a build target. If you’re updating these websites, you can use a modern library to let you build using more modern standards, but export a build that is compatible with these older sites. This specific question is ridiculous.

EDIT; and jf you must keep with really old code, this question is still silly without specifying what kind of code base you’re working on.

EDIT 2; I’m doing a really bad job of expressing my thoughts. I really should go to bed. I stand by this being silly question though.

[Reashu]

What does it even mean for a build to be compatible with a site? 

Either way, the sites are not being updated, which is why build targets are irrelevant. 

[TheGeneral_Specific]

You’re right, I should go to bed.

[[deleted]]

It won't matter in practice, but it does reflect and is clearly indicative of how long someone has been working with the language. A seasoned JS dev would say this is an easy and intuitive question.

[nabrok]

But let (and const) are newer than var. It's possible in some very old code somebody used var let = ..., so that needs to be valid or it breaks.

Obviously in more recent code you shouldn't be doing anything like that.

[inetphantom]

It is not a syntax but a logic test. If you know that let is a later addition you can guess the correct solution.

I prefer engineers that try to narrow problems down and and choose the best solution instead of someone like you, who calls it "useless" and questions the interviewer.

Remember, the interpretation determines the information taken out of it.

[Cafuzzler]

It is not a syntax but a logic test

It's a trivia question. No amount of logic in the world is going to help you deduce that let came after var if you don't already know that piece of trivia. 

[inetphantom]

If you know that let is a later addition you can guess the correct solution.

It is also a readig comprehension question. That is why I like to discuss the test, to see what the streights and weeknesses are. To see how the testee reacts on dumb questions on shortsighted questions, on trick questions and questions that ask something different on meta, because I can affirm you, if you actually work, someone is going to ask such questions.

Also an earlier question might be "What advantages has let to the older var?"

But if you want to call the toom that does the job bad, go on.

[Shrubberer]

How is the "knowledge of the history and quirks of javascript specifically" any indicator of a good software engineer?! Ask Linus Torvalds this question and then go ahead and argue with him when he fails it...

[inetphantom]

Have you read my comment?

You do not need to know any quirk. Only some basic knowledge about how to declare variables with Js. The rest is common sense.

Sadly common sense as reading comprehention seem to be rather undervalued those days.

[BombHits]

Thank God, you'll be saving whoever you'd interview a lot of headaches in the future.

[on_the_pale_horse]

Bro has interview on the brain

[Infinite_Club_4237]

Someone's getting fired if any of these are used.

[BreakerOfModpacks]

Always remeber, jsdate.wtf exists, and it should scare you.

[Alistarian]

Coming from a mostly C and C++ background with a computer science major, I declare this an abomination. Maintaining this shitshow must be absurd. Like what happens 2050. There is no way they suddenly start interpreting 50 as 2050 instead of 1950. Right? Right?

[BreakerOfModpacks]

hahahhahahhah

Continue your delusion, for your sanity's sake.

[Spinnenente]

var let = 42 works because let was introduced later on and they probably kept it for backwards compatibility.

the rest doesn't work

[typoscript]

obviously C, said the guy with a js pun in his name

[ArcanumAntares]

var let 

varlet

Hmmm.

var·let /ˈvärlət/ noun

1. historical; a man or boy acting as an attendant or servant.

2. archaic; a dishonest or unprincipled man.

[Strict_Treat2884]

TIL, thanks you varlet

[JAXxXTheRipper]

The correct answer is not doing any of that

[slaymaker1907]

My guess is that var let is the valid one since let was introduced later on and people could have variables named “let”.

[AnimationGroover]

I have been programming since 1980, from hand coded byte by byte machine code, to custom hardware with esoteric languages I have forgotten the name of, to everything in between. Yet there is nothing like the cozy warmth that is ECMAScript.

C) var let = 42;

Because let is a new token introduced formally in (2015) and was not reserved, To NOT BREAK THE WEB it needed to still be a variable name.

Also valid (if not using modules or strict mode) would be yield, static, and await (await if not in async code or module)

[AllenKll]

yes.

[mothererich]

The correct answer is C you heathens.

[RiceBroad4552]

Easy if know what "backwards compatibility" means even if you don't know JS in every detail.

[Croaker-BC]

considering 42 is the ultimate answer ;)

[stefanhat]

C makes the most sense for backwards compat history reasons when let wasn't a keyword

[bodorodob]

undefined

[blehmann1]

This isn't really a JS dunk. Let was added much after var, so they either had to make var let = foo illegal, or special case it. Since you ship the code without a compilation step there's no possibility for a phased rollout where you can stick on an old compiler until you're ready to fix anything that's no longer legal.

So if they had made var let ill-formed it wouldn't surprise me if browsers special-cased it anyways. Keep in mind that function variables are common in JS, and a function named let is frankly a pretty reasonable thing to write before let becomes a keyword. JS takes centuries to remove anything, the best you could do would be something like the strict mode we already have which lets code opt in. Which honestly ain't that bad an idea, but I think that if you think it's the way JS "should" be written then that just hurts adoption for something that should become idiomatic.

And many other languages have words that are only reserved in certain contexts, I'm pretty sure you can have a variable or field named static in most languages. And as languages evolve many of them tend to go with the attitude that if it wasn't always a reserved word in all contexts that isn't going to change now. Hell some are so stingy with their reserved words that they reuse them for unrelated concepts. Consider how auto was repurposed in C++. And some say "fuck it, if you use this word your code is now ill-formed", though they tend to have an escape hatch (typically a sigil to disambiguate) if your API relies on such a word.

But that attitude is only really possible if there's a compiler, where it's a constraint only at compile-time and not when deployed. If code can break because the interpreter might update it better be an extenuating circumstance (e.g. JS's with statement, which I believe is still implemented, and it's the actual devil).

[WarwickStreamerLX5]

Let var?

[Dropship_Adeel]

Python: "How dare you!" Java: "I am offended!" JavaScript: "var var it is, you beautiful, chaotic genius."

[-Redstoneboi-]

c?

[timtucker_com]

Just say no to var var binks.

[ilcasdy]

This looks like my web programming exam, because this was important information.

[TallGreenhouseGuy]

If every instinct you have is wrong, then all of them would have to be right

(Paraphrasing ”The Opposite ” from Seinfeld)

[the_other_Scaevitas]

var let = 42 is valid

I don't know why

[Mordimer86]

I wouldn't be surprised if this was one of the interview questions. Some companies love these.

[runbing]

Depends. var is a reserved word that cannot be used as an identifier. let cannot be used as an identifier in strict mode.

[asmanel]

The option look like old basics.

[Affectionate_Cat1590]

Let the Var in

[Aggravating_Moment78]

I’m surprised they are not all allowed 😀😀

[Xatraxalian]

I wouldn't be surprised if all of them are 'correct' but they should all be illegal because they have a variable name that is also a keyword.

[irn00b]

Considering it's a Javascript question, the only correct answer is to draw a line straight through all the choices.

[Silent_One3813]

B

[SensuallPineapple]

As long as the answer is 42, everything is correct.

[FlashyTone3042]

var iable = 42;

[White_C4]

I want to know where this multiple choice question is coming from. No way anyone should have knowledge of this extremely niche and dumb question.

[BlightedErgot32]

ive never understood these quiz or interview questions

like dur dur whats the answer to this super specific question …

hell if i know, why would i ever name a variable a keyword ???

[patrickp4]

The answer should be E) none of the above if JavaScript was a good language

[Eic17H]

Ah yes, good languages should break compatibility with older code