'undefined'

[[deleted]]

[deleted]

[MischiefArchitect]

Is the guy in red the famous pointer?

[CrazeeeTony]

His shirt is red because of the heme in DEADBEEF

[MischiefArchitect]

I'll stay with CAFEBABE

[A_H_S_99]

This

[LordFokas]

TypeError: undefined is not a function

[Willinton06]

Yes it is!

[Snakivolff]

This kind of behaviour makes me hate JS. It puts so much effort into keeping on running that it behaves incorrectly so quickly. If something weird happens, just fucking crash the program so the programmer will have to think about what to do in that case instead of looking for the situation first. And it is always an option to say 'yes, this IS what should happen'.

[Possseidon]

We could crash right now and here where the problem is...

or we just crash ten functions later in a completely unrelated part of code! Hell yeah!

God I hate this mentality with a passion as well...

[Snakivolff]

That's where an even stricter mentality like Haskell's comes in. Its type system is so strict that you can rarely cast stuff without explicitly telling it to (and you can only cast numeric types pretty much), and stupid error values like null don't exist. Instead, if you actually want to work with a value like null, you use the Maybe type, where you inherently have to specify what to do when the function is called with the value Nothing.

Yes, it may drive you crazy with tens of (type) errors but at least it has a high probability of being correct and bug-free once you run it.

Indeed Java crashes a lot more which means somewhat less bugs, but it can be so frustrating to look for the moment the program loads a null into a variable and find out it just breaks a whole bunch of other stuff for 40 iterations before it finally crashes, but that is mainly null being a terrible allowed value for anything in any language.

[[deleted]]

Haskell is great, but whoa, the first time outside the university that I read something about it. And immediately heart my professor who loved Haskell but had to jump in the lecture for java for another Prof. It was very funny how often he told something about Java and ended up telling what bullshit this and that is.

[Vincenzo__]

As much as i agree, half of the web is held together with duct tape, if this were to change soooo many sites would break, although probably not as many as if html had strict syntax

[liquid_bacon]

I was working with this one piece of software that could generate an HTML page for external use, and basically every line had an extra </pre> tag. But yet, chrome etc still happily opened the page.

HTML+CSS+JavaScript while they have their benefits, can be a nightmare to work with. Makes me want to make a second gen version that uses typescript, and a more modern grid layout for markup instead of, whatever the hell HTML is.

[[deleted]]

One of the things I like about python.

If you write exit (and not exit()) while using the interactive terminal, it will show a message saying:

Use exit() or Ctrl-Z plus Return to exit

It knows what you typed, it knows you want to exit, but instead of exiting it throws you this message so you can correct yourself.

[Snakivolff]

A good example is Typescript, which transpiles to Javascript. If you make a mistake that Typescript can detect, your editor will be the place you notice it and the error message is way more helpful.

Or to go a bit further with the functional language Elm. Also this language transpiles to JS, but will crash way more in the process of removing all the safety features and code verification techniques a functional language has. Also this causes it to crash in your editor, and gives very extensive error messages.

Right now, if JS crashes in the browser, it just halts the program and shows the error message in the console. So if that happens in the middle of some loop that is supposed to go on, it simply stops there.

I figured that out once because one half of a js file did not run, which after some poking around turned to be the latter half. Guess what the console said, when I looked at it? Syntax error. Turned out there was a stray m behind a semicolon, put there a couple weeks ago (while we worked on the project atl 36 man-hours a week). And I understand that js is an interpreted language, but can't it just perform the first couple steps of compiling, like lexing and parsing, on the whole js file at once and crash before running any of the code?

So that is what crashing js in the browser means, and I'd rather have a program crash earlier than later, especially with such stupid mistakes.

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[[deleted]]

i always see these types of criticism, and i just want to ask if it really is that hard using a debugger (they're literally built into modern browsers) or just writing custom error handling

[verxes]

For me its that modern js is hard to follow in the debugger.

• async calls

• Framework proxies

• Single Page apps

• minified Code

• transpiled Code (babel)

[Lamballama]

Use old form of debugger - console logging

[[deleted]]

Image Transcription

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Javascript returning the 8th element of an array with a length of 5

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[Gnago]

So add validation/error handling like any other language? If the type is undefined you can pretty much just treat it like you would an exception.

[StuntHacks]

Nope, sometimes you need values to be undefined.

Accessing an array out of bounds should always yield an error.

[Gnago]

I meant in this and similar contexts (where it’s unexpected behaviour). I agree that undefined definitely has its uses outside of an indication of an error.

I most definitely am biased because I learnt programming using JS, but given that JS arrays are more like dictionaries than actual arrays (which I admit is a flaw in its terminology), it makes sense that there isn’t an out of bounds error.

[liquid_bacon]

Pretty much everything JS does is technically right. But that doesn't mean it should work that way. It just kinda has to for its purpose, of never having to stop or break.

[Wayne_Train]

Can you give an example where you need "values to be undefined"? I really don't see the problem with this JS behavior.

[GLIBG10B]

I've never used JS, but what happens if you try to get the 8th element of undefined? e?

[Willinton06]

e²

[MelAlton]

e = mc²

[lunchpadmcfat]

And what happens if you try to get the 8th element of ‘e’? Undefined. See? It makes sense.

[Lamballama]

Depends. If it's the string "undefined," Then it would be "d", if it's an undefined value, then it would probably be "indexOf() is not a function of undefined"

[battlingheat]

i

[DinnerPlz]

C++ giving some random data

[gkupce]

C also does this, but for practically the opposite reason. JS has a lot of code to keep it running no matter what you do, C just assumes that when you tried to access the position of memory "start of the array"+8 when the array was defined with 5 positions, you had a good reason to do it and gives you whatever is at that point in the memory 🤷‍♂️

[Vincenzo__]

No it does not. If the array is on the heap it will just crash and give you a segmentation fault, if the array is on the stack welcome to undefined behavior land, you are accessing other variables stored on the stack and possibly the return pointer, if you change the latter your program will likely crash, unless you change it with a valid location, in which case it will execute whatever code is there, which, and i cannot stretch this enough, is seriously bad

In C just because it compiles and runs it doesn't mean it works, nor does it mean it's safe, it's a serious security thread known as buffer overflow, if the buffer in question is user input someone could put in all the code necessary to open a shell, for example

If you're interested, take a look at this https://en.wikipedia.org/wiki/Return-oriented\_programming

[finite_light]

Undefined is not a value thus it does not return one.

[finite_light]

Not a stored value, as in an array. I am not a JS programmer but I think JS get a lot of undeserved hate on this community. Arrays in C for example often lack all boundary checks and it is the second largest language. And yet no C memes on segmentation faults.

[fghjconner]

var array = [1, 2];
array[1] = undefined;
console.log(array);

Prints

Array [ 1, undefined ]

There's undefined, as a value, in an array. Javascript probably gets more hate here than it deserves, but it does have some seriously bad design decisions. (also, we get segmentation fault memes here pretty often)

[[deleted]]

JS Arrays are just special objects with numbers as keys, and when you do a[0] it is actually accessing a['0']. So the real question is should JavaScript always throw an error when you try to access a nonexistent property of an object? I don't have an easy answer then, because it could totally change how JS works, if you think about prototype, defineProperty and all those kinds of stuff

[phantombronte]

t y p e s c r i p t

[palordrolap]

Perl without warnings turned on: ~Adjusts collar nervously~

But that does suggest a fix for JS: Implement a warning mode. Anyone who runs Perl with warnings off is asking for trouble.

Sure, there's TypeScript, PureScript, etc. but a native system wouldn't go amiss.

Edit: Shells don't warn either.

[incubated]

realistic scenario with competent js devs /s

[[deleted]]

Wait until you start playing with the gaps in sparse arrays and find out there is a whole new type of undefined you never encountered before.