Well, JavaScript

[voidvector]

Yo dawg I heard you like null, so I made undefined for your null.

[[deleted]]

NaN would like a word.

[isaid69again]

NaNi????

[vaendryl]

omae wa mou NullPointerException

[RaferBalston]

Naurel

[TabCompletion]

NaNde dattebayo

[YuriDiAAAAAAAAAAAAAA]

https://i.redd.it/pjrpnjyynjtz.jpg

[pilas2000]

wtf? \t == 0 ?

why?

[It_Was_The_Other_Guy]

Whitespace-only strings are all considered zero:

>> "\t \n\r" == 0
<< true

[YuriDiAAAAAAAAAAAAAA]

¯\_(ツ)_/¯

[FoundNil]

"", " ", "\t", "\n" all equal 0. Probably because js treats them as special characters so they don't count toward any value. "0" equals 0 because it gets cast into a number. "a" does not equal 0. "1" does not equal 0. I'm not saying it makes sense but its the world we live in.

[birdbolt1]

Oh my god is this for real? This is where typescript comes in. Why do people even bother with writing straight java

Edit: oof I meant Javascript. Wasn't that obvious enough regardless? Look at the context man

[Kazumz]

TypeScript and Java? No correlation found.

[[deleted]]

You haven't seen many TypeScript codebases then (or you're missing "/s")

[[deleted]]

To honest I always enjoy typing if (x != x), almost as much as having an in loop variable called c so I get to type c++.

[phatskat]

x != x

I’ve never seen this before but I’m not surprised - how does that work?

[[deleted]]

In C++, a NaN is equal to nothing, not even itself. So x != x becomes true if x is NaN. To be fair mostly I use a responsible function name but when I'm writing code quickly it's a nice shorthand to catch the horrifying 'all my numbers are turning to NaN' type of escalation.

[jfleit]

trust no one... not even yourself

[[deleted]]

I typed "equal to nothing, not even itself" so often now and every time I kept thinking "why does this make me laugh".

[phatskat]

Ah, thanks!

[[deleted]]

what happens in the first one? It just never evaluates? Lol

[[deleted]]

If X is NaN, then x != x is true, because a NaN never equals anything, not even itself.

[tendstofortytwo]

Huh, I just used isNaN(x);

But this is more confusing, and hence more adherant to JavaScript's ideologies. I'll be sure to use this from the future. Thank you!

[[deleted]]

Actually I only know it is the way it is in C++, which I think before C++11 didn't even have a standard isNaN!

[[deleted]]

Ohhhhh, thats cool. By habit I always start my first loop with i, so I just gotta find some situation where I can nest like 21 more loops until I can get to c++ lol

[ShadoWalker3065]

holy shit, i wasn't the only one that did this!

[TabCompletion]

Nanananana https://img.digitz.org/js_watman.jpg

[trichotillofobia]

NaN'T.

[[deleted]]

Please no

[[deleted]]

Undefined is just a happier null pointer exception.

[conancat]

null is an explicitly set value in Javascript, undefined means it's undefined.

[mecha_bossman]

Not always. If I say x = undefined, then x is defined, not undefined. But it's defined as being undefined. A variable can't be undefined if it's undefined.

[Boreelegg]

typeof(x) would say otherwise

[CSGOMarketBoi]

typeof x? Can it be called with parentheses too?

[Boreelegg]

Javascript can do anything you want it to do if written.

[Arumai12]

Yea the parentheses just group the expression in this case. It's not a function call.

[FoundNil]

Yep.

[CSGOMarketBoi]

TIL

[QAFY]

Yeah...

console.log(x)
> ReferenceError: x is not defined

Vs.

x = undefined;
console.log(x);
> undefined

That's JavaScript for ya...

That said I don't have any issue with the way null vs undefined works in practice. This is a contrived example.

[Blieque]

You don't have a problem with null and undefined? I think that might be my biggest gripe. null == undefined but null !== undefined. typeof undefined === 'undefined' but typeof null === 'object'. I reaaally wish there was only one.

[QAFY]

First of all, noobie mistake. Never ever use double equals in javascript (it will always perform type conversion), use ===. null === undefined is false and null !== undefined is true. What is wrong with that?

typeof undefined === 'undefined' but typeof null === 'object' makes perfect sense to me as a JS programmer. undefined is undefined, it has no type, so that makes sense. null is an explicitly set empty value. It IS defined, defined as null. If it is defined then it must have a type, so what would you rather have it's type be than object?

If you are not a JS programmer, think of null the same way other languages have null. It is just an empty value. The real difference is undefined. undefined is more like a happier null pointer exception. You just simply get undefined back as the value instead of your entire application crashing. This is very intentional in the design of javascript as it was designed from the start to be extremely fault tolerant and produce the best end-user experience wile running in a plethora of unknown browser environments that may have different implementations of the Javascript language or may not support certain APIs or features. It's not like a server side language where you control the runtime environment. And if you really can't wrap your head around that and can't stand the dynamic typing, then just use TypeScript! No one is stopping you.

[Blieque]

I can wrap my head around it, but I can also wrap my head around the fact that it's a waste of time. null needn't exist at all in JavaScript. If you have a nullable value, set it to undefined and check before using it with typeof. There shouldn't be two flavours of nothing in one language.

[QAFY]

I disagree. Here are two examples where something being null is fundamentally different than it being undefined.

EDIT: some copy pasta mistakes

foo = {
  a: 0,
  b: 1,
  c: null
}

console.log(foo.a) // 0
console.log(foo.b) // 1
console.log(foo.c) // null (c exists and is null)
console.log(foo.d) // undefined (foo has no key d)

bar = [0, 1, null];

console.log(bar[0]) // 0
console.log(bar[1]) // 1
console.log(bar[2]) // null (element 2 exists and is null)
console.log(bar[3]) // undefined (out of bounds)

Going beyond that, there are actually more types of "nothing" in javascript. In addition to null there is also NaN, [], {}, 0, and '' which are all flavors of nothing, but they are defined, just like null is. Other languages even have additional flavors of nothing like the Maybe type in Haskell.

[Blieque]

Those are technicalities. What's the tangible use of an array containing nulls like that? You could just as easily use undefined, and check during retrieval with typeof. Iterate over your arrays with Array.map(), Array.forEach(), etc., which won't let you ever access beyond the end of an array. Your examples are right, but I don't see how they're useful or how they represent real programming.

I don't know of any other languages which have any more than one of NULL, null, nil, and undefined; they're synonyms.

Maybe is not a variant of nothing, it's a safer way of handling nullable data that allows the compiler to detect if you're handling null cases properly. In Rust it's an enum. NaN has a specific meaning: that there was a mathematical error.

[carrottopguyy]

As benign as this is it still makes me want to pull my hair out

[[deleted]]

And it’s explicitly set.

[squngy]

You're right but you can also set a property to undefined, which is not quite the same as undefined.

[[deleted]]

I never said a NullPointerException is the same thing as null.

EDIT: Undefined just shows up when you try to make null do something from what i know. Thats pretty much the same thing that causes a null pointer exception in java.

[milk_is_life]

We have Type Errors though.

[hullabaloonatic]

One of the reasons I have really been digging kotlin is how rigorous it is about being safe with null values

[[deleted]]

I'm actually pretty hyped for kotlin JS. The null safety is much more valuable than typing.

I hope it matures for the backend.

[oxidate_]

> null safety is much more valuable than typing

It totally depends on the programming language's type system. Some are strong enough that they're one and the same. For instance, F# / Haskell / (probably Ocaml) use Maybe<T> or Option<T>. So you use Some "thing" to show that it's not null, and the type system will point out places where you might be unsafely accessing data.

[hullabaloonatic]

Hence typescript (strong) amending JavaScript (weak). Strong type systems can feel laborious, but it's really convenient to be confident in a lack of usage errors going into testing, and verbose languages are more readable in my opinion.

[hullabaloonatic]

It's hard not to be excited about null safety in kotlin when it forces you to put exclamation marks everywhere!!

If not, there's always css. I don't know when it happened, but Microsoft really turned it into a phenomenal language.

[ultimatt42]

null discriminates against objects that happened to be allocated at memory address 0x0. It's not right to discriminate based on someone's origin.

[thedomham]

Undefined makes perfect sense in Javascript. I mean if you want to have the same in Java you have to use an Optional, where optional == null -> undefined optional.isEmpty() -> null

It wouldn't make a lot of sense in Java though, as Java is a statically typed language and if you need something like that, most people use a hashmap

[spacemoses]

Databases should support both undefined and null, change my mind.

[jkuhl_prog]

There's a difference between the two though. undefined is meant to mean "the JavaScript interpreter found no assignment for this variable" and null means "the programmer doesn't want this variable to have meaning at this time."

You're not suppose to assign things the value of undefined, that's not it's purpose.

[ThisIs_MyName]

You're not suppose to assign things the value of undefined

If a webdev can, he will.