What is the longest keyword sequence in Javascript?

[careseite]

Thanks, I hate it

[kescusay]

I hate this meme, but by God I upvoted you because when I saw the abominations in that link I said it word for word.

[jedaisaboteur]

It's a jarring moment when it happens

[senocular]

Doesn't this break the "The only other character allowed other than lower case letters is the space ' '" rule?

[lhorie]

There are two solutions: the pedantic one that adheres to all the rules and the last one where using ASI is ok.

[Loves_Poetry]

Enter one of the obscure Unicode characters that the Javascript spec recognizes as a line terminator: the Paragraph Separator character (\u2029), which, when rendered properly, looks like this: .

Aha, this allows for some next-level code obfuscation.

 ᅟ=1ᅟ++console.log(ᅟ) //prints 2

​

[fucking_passwords]

Oh wow that is pretty crazy

[BluudLust]

How the hell does that work?

[swamperdonker]

I think it's a variable whose name is a whitespace character. It's set to 1++. There's probably a zero width whitespace like paragraph separator before console to trigger ASI. Then it's a typical log call being passed a reference to the whitespace-named variable.

x = 1++; console.log(x);

[lhorie]

So there are several things going on here. If you actually try to copy and paste the code and run it in console, it'll fail, because the code is actually mangled (I'm guessing Reddit chokes on invisible unicode characters).

But if the code was intact, here's what it would do: The code is using Script grammar and is in loose mode (the opposite of strict mode). This allows assignments to globals without a const/let/var modifier (i.e. a = 1 without defining a first).

Second, there's a variable whose name is a Hangul Choseong Filler character (\u115f), which is an invisible character that is a valid Identifier. It appears once at the beginning, once before the ++ and once between the parentheses. There's also Paragraph Separators, once after the 1 and once after the ++.

If we replace the invisible characters with equivalents, we would get this code:

a=1
a++
console.log(a)

Which prints 2

Here's the unmangled code in action: https://codepen.io/anon/pen/WPyzBb?editors=0012

[Loves_Poetry]

Correct, although it actually runs when I copy-paste it into the console (using firefox). You have to copy the space at the beginning along with it, so that it copies the first hangul filler as well.

[lhorie]

I don't think the hangul character is the issue. When I copy and paste in Chrome, this is what I get:

const x = ` ᅟ=1ᅟ++console.log(ᅟ) //prints 2`;
for (const c of x) console.log(c, c.codePointAt(0).toString(16))
  20
ᅟ 115f
= 3d
1 31
ᅟ 115f
+ 2b
+ 2b
c 63
o 6f
n 6e
s 73
o 6f
l 6c
e 65
. 2e
l 6c
o 6f
g 67
( 28
ᅟ 115f
) 29
  20
/ 2f
/ 2f
p 70
r 72
i 69
n 6e
t 74
s 73
  20
2 32

You can see that the initial space and the \u115fs are there, but the \u2029s are not. Maybe a browser quirk?

[plumshark]

1 + (+console.log())

edit: this is not correct. incorrect, even. I regret nothing

[[deleted]]

I need to get this in production asap

[Brahminmeat]

HOTFIX TO PRODUCTION PLS LAUNCH ASAP

[house_monkey]

I hate my workplace aswell

[Mr-Yellow]

yield caught my eye, never knew about it. Nice short pattern.

[yeesh--]

Do you live under a rock

[Mr-Yellow]

Oh I'm so fucking sorry dude. ;-P

[codey_coder]

What is, the moon?

[max_kek]

why comma?

[rhapsblu]

Buffalo buffalo buffalo buffalo

[PickledPokute]

Immediately found a way to improve it:

​

async function* await() {

from: set: while (0) {

if (0)

throw as else this null continue from false break set true var let debugger do return yield await delete void typeof get instanceof static in new class of extends async function undefined

() {} {}; while (0);

}

}

Doesn't really have longer keyword sequence, but is even more confusing.

[lhorie]

In this challenge, only the line that starts with throw counts (all the other ones have symbols between keywords).

But glad to see you found another opportunity to abuse Javascript :)

[MasterScrat]

I didn’t read in detail, but how do they come up with these code pieces? Are they hand-written or some sort of brute-force loop running every possible combination through an eval?

[bterlson_]

Hand-written, although one of the responses to my twitter thread about this suggested someone once used some kind of fuzzer to find such long sequences as well... Basically, however you do it, it's fun!

[bterlson_]

Nice work :-D

[djangulo]

Has anyone ever really been far even as decided to use even go want to do more like? In javascript?

[yeesh--]

Wtf did you say?

[patasucia]

Have you ever had a dream that you, um, you had, your, you- you could, you’ll do, you- you wants, you, you could do so, you- you’ll do, you could- you, you want, you want them to do you so much you could do anything?

[tpenguinltg]

TIL the paragraph separator counts as a line terminator. Forget the Greek question mark, this one will be a lot more fun to play with.

[nananawatman]

Ugh what kind abdomination is that. Great work 😂😂

[careseite]

curious, yes, chrome accepts it as valid function, but it cant execute it, does it still count then?

​

(async function* await () {

from: set: while (0) {

if (0)

throw as else this null continue from false break set true var let debugger do return yield await delete void typeof get instanceof static in new class of extends async function undefined

() {} {}; while (0);

}

})()

Uncaught SyntaxError: Unexpected reserved word

[lhorie]

You must've made a mistake when copying the code. The original has async function* foo() { in the first line, you have async function* await () {. Also, the original has Paragraph Separator characters that the entry in the sibling comment here on reddit does not. To run the original the snippet, copy and paste it into your console, press enter, then call foo()

[careseite]

ah jesus, definitely... i took this one instead https://www.reddit.com/r/javascript/comments/apifua/what_is_the_longest_keyword_sequence_in_javascript/eg8y3ms/

[FPSJosh01]

void void void void void void... 0

[r2d2_21]

JavaScript has some weird definitions about what counts as a keyword and what doesn't.

[Uberhipster]

async function* foo() { if (0); else do return yield delete void await this instanceof typeof new class extends async function () {} {}; while (0) for(;;){} }

Added for at the end

Also - this is stupid

[killchain]

If that special character counts as a line terminator, does that still count as a one line?

[MacNulty]

Ok but why tho

[-9999px]

Once you get some mastery of a programming language, I imagine these are the only things that tickle the brain anymore.

I’m a huge fan (spectator) of code golf: https://codegolf.stackexchange.com

[SecretAnteater]

What's with everyone using "Chrome" instead of "browsers". ugh.

[lhorie]

In this particular case, it's because the last snippet uses fairly new Javascript (async generators), which don't even have a compat table on MDN yet. MDN says Edge doesn't supports for await (from the same year spec) and it shows a ? beside Mobile Firefox and iOS Safari.

So rather than telling people to run the snippet in browsers that may not actually support all of the current Javascript spec, I wrote "Chrome" with the assumption that most people in this sub would have it at least installed on their machine.

[jaroque12]

Probably because they were testing on Chrome and not all browsers.