You Can't JavaScript Under Pressure

http://toys.usvsth3m.com/javascript-under-pressure/

by jgv • 13 years ago

72 105 13 years ago

toys.usvsth3m.com

tomscott• 13 years ago

Oh! Hello. This is my thing I made for usvsth3m.com. Hope y'all like it. HTML5 Webworkers made it possible - sandboxing user-submitted JavaScript so an accidental while(1) or document.write can't kill everything.

Do have a look at the source code. Oh, and try turning up your speakers and typing in the Konami code...

JosephRedfern• 13 years ago

If you alert() something inside an infinite loop it doesn't seem to be able to detect it (nor does it show an alert box!)

Demiurge5• 13 years ago

Nothing like figuring out another way to kill your browser :)

TazeTSchnitzel• 13 years ago

Oh, you, Tom Scott, made it? :D I'm a big fan.

A few suggestions, then:

1. Don't use i as the name of the parameter. A lot of people use that as the name of loop variables, and it means breaking habit or wasting time changing the name.

2. For test 3, try some multiple-extension files to make sure they did it right (some.file.multiple.extensions, should return "extensions")

3. For test 5, it says "integers". Try some non-integers during testing, to make sure that it's only checking for integers.

4. For test 5, it says "arrays". Try some objects to make sure they're not being lazy and using typeof thing === "object"

Anyway, thanks for making this. I love it!

cheshire137• 13 years ago

The sudden music/talking that started was annoying and caused me to close the tab immediately.

brudgers• 13 years ago

No NoScript?

Kiro2• 13 years ago

Are you seriously using NoScript? I thought it was a myth.

tonyarkles2• 13 years ago

Maybe I'm naive but... I suspect that the rest of the page wouldn't have worked with NoScript. Since you're, you know, typing in JavaScript code and running it against some test cases.

prezjordan• 13 years ago

Lighten up, everyone, this is a fun little thing. Thanks for sharing.

mikeash3• 13 years ago

Thanks for immediately playing audio without asking me first. I know everybody just loves it when web pages do that.

corresation2• 13 years ago

Because of your comment, HN will have a dozen "I am so disappointed in all of you" posts in the coming week declaring how mean everyone here is, and how it is no longer like it "once was".

I hope you are happy.

mikeash3• 13 years ago

I'd be happier if this page hadn't blasted music into my conference call.

skrebbel• 13 years ago

I love how you're mocking HN and the parent post at the same time!

buckbova• 13 years ago

If using chrome, the Chrome Toolbox has a handy mute all tabs feature. I have it muted by default.

https://code.google.com/p/chrome-toolbox/

Demiurge5• 13 years ago

That's great! Here is the actual plugin I had to look up: https://chrome.google.com/webstore/detail/chrome-toolbox-by-...

ryanthejuggler2• 13 years ago

Could there be a histogram at the end that shows distribution of finishing times? Or at least a leaderboard... I did pretty well [obviously ;)] but I'd like to see where my time falls in relationship to others.

I've confirmed that I can, in fact, code under pressure, but to what degree?

Other than that, fantastically fun game. My only regret is that it's a one-time game by nature, since obviously the second time around you'd simply be remembering what you did the first time instead of creating it.

Aco-• 13 years ago

A lot of people posted their results to twitter, you can get an idea of where you fall in avg by giving this a glance over:

https://twitter.com/search?q=I%20completed%20%22You%20Can't%...

ep1034• 13 years ago

What's everyone's times? I did 7 minutes

Justin_Time2• 13 years ago

4 minutes, 56 seconds for all 5 levels. Well done!

mneary• 13 years ago

Just under 3 minutes!

hatsuseno• 13 years ago

My JS is somewhat rusty, glad I had a .map() to work with. 9 minutes something, I did 'cheat' by looking up some typeof returns.

CompelTechnic• 13 years ago

17 minutes, 47 seconds. slow poke here.

dclowd99015• 13 years ago

26 Minutes. If you're a slowpoke, I'm a Slowbro.

robflynn2• 13 years ago

"2 minutes, 32 seconds for all 5 levels. Well done!"

The "kill screen" song is stuck in my head now.

trevordixon• 13 years ago

4:20.

renekooi• 13 years ago

2:26.

methodover• 13 years ago

14 minutes, 27 seconds for all 5 levels. Bah, should've done better. On the other hand I just woke up.

I wanna see one of these in Python.

Demiurge5• 13 years ago

12:45

ryanthejuggler2• 13 years ago

3:15

nakovet• 13 years ago

I only did one time: 8 minutes and 57 seconds, for sure the next try will be way easier.

dmak4• 13 years ago

11 minutes 14 seconds. I wish I did faster!

dpedu• 13 years ago

6:11.

Blew through the first 4 but spent half my time on the last one because I don't have Javascript type checking memorized.

myh• 13 years ago

5 minutes, 31 seconds for all 5 levels. Well done!

oftenwrong• 13 years ago

8:30

Spent nearly the entire time on #3 because I was trying to use String.replace to work and failing. Ended up using .split instead, which passed thanks to poor test coverage (just like at work!).

EdgarVerona2• 13 years ago

8:11 for me - as it sounds like was the case with others, the majority of that time was searching for how to check for specific types in Javascript.

For the "is this actually a string?" check, for example, I started looking for the existence of the match method on the object, which of course would have failed if they passed some random object with match defined so I cheated a bit. I'd like to see the full breadth of test options people took out there.

leehro• 13 years ago

This was awesome. 5:48. I actually turned my sound on for the end.

kirse3• 13 years ago

Fun little puzzles. First 4 went pretty quickly (~8:00) and then the last one took ~7 minutes Googling around for this so I could test if a variable was an integer...

  n===+n && n===(n|0)

Wish I could see my answers after the fact though!

Edit: Read the initial requirements of the puzzle, it says sum all the integers, not all the numbers. People using (typeof i[x] == 'number') just got lucky because the test-cases didn't exercise the full requirements of the puzzle ;)

  // i will be an array, containing integers and/or arrays like itself.
  // Sum all the integers you find, anywhere in the nest of arrays.

Justin_Time2• 13 years ago

typeof n === 'number'

It didn't actually require differentiating between integers and floats, just numbers and other types.

solox3• 13 years ago

    > typeof 5.4
      "number"

iainnash• 13 years ago

This typeof stuff (and having number instead of integer, string, etc) was the hardest part of this for me.

Normally javascript function inputs aren't this messy.

kentor• 13 years ago

    n % 1 == 0

kirse3• 13 years ago

Tried that first, but that will fail on the "false" case.

chrisrhoden2• 13 years ago

n===~~n

downtowncanada• 13 years ago

if(typeof i[p] === typeof 3){//it's an int

  sum += i[p];

}else if(typeof i[p] === typeof [3]){//it's an array

  recursion(i[p]);

}

pretty simple no?

cs02rm0• 13 years ago

That would've been simpler, but I seemed to get away with typeof(i[p]) === "object" and typeof(i[p]) === 1*typeof(i[p]) to test if it was an int.

I dread to think what obscure code I've left behind.

chrisrhoden2• 13 years ago

no, in this case the first will match on all numbers and the second will match on all objects.

You should learn a little more about JS before you call this simple.

Bahamut3• 13 years ago

It was a kinda cool thing, although I got some strange behavior when I was using `match` for determining whether the input is a filename - my regex was /.\../ (and so I did var match = i.match(/.\../) ), and match[1] was undefined - turned out match[2] was what I wanted, and it was present, but the behavior was incorrect in the reporting console in the game.

I finished this in 4 minutes.

Edit: looks like HN doesn't like asterisks

tensafefrogs• 13 years ago

I thought regex was overkill for that one and used:

return input.split(".")[1] || "";

dclowd99015• 13 years ago

I fully anticipated a test case like file.name.ext. Of course, you could still do what you're doing, but it'd be a lot more verbose.

Bahamut3• 13 years ago

What if it had multiple dots? Anyhow, I am on 5 hours of sleep, and already s spent6 hours coding...I just wanted to finish fast.

axyjo• 13 years ago

"6 minutes, 21 seconds for all 5 levels. Well done!" I feel like I should have done better considering JS is one of my primary languages.

Demiurge5• 13 years ago

That was fun! I just got in to work so I was properly sleeping. I also rarely use typeof, so I had to look up that 'integer' and 'array' do not exist :) Also, what was really annoying is the use of 'i' for the argument. That's what I exclusively use for the 'for loop' index! Tripped me up a lot, I had to consciously remind myself every time I accessed the array. Last 'also', the font is WAY too big for my small screen, the comment never fit in, I had to scroll... So I think I did bad, 12 minutes. But still fun :)

robflynn2• 13 years ago

The use of 'i' set me back a bit, too. Caused me to go into an infinite loop at one point.

daGrevis• 13 years ago

Exactly this. I had to rename `i` for indexes to `j` and that really messes my head up! :(

peeters• 13 years ago

Fun distraction. For me it was:

30% figuring out the answer, 20% not having my editor shortcuts available, 50% figuring out how to check if a value is a certain type.

Am I the only one that gives their functions preconditions that the input is good? To me, throwing up when you're passed a non-number to a sum method is correct behavior.

dclowd99015• 13 years ago

TIL there is no typeof === 'array'. -_-

ep1034• 13 years ago

Array.isArray(yourVariable), yeah, had to mdn that one too.

rhengles• 13 years ago

    [] instanceof Array; // returns true

hayksaakian2• 13 years ago

typeof(["an array", "contains multiple things"]) == typeof(["sometimes"])

Kiro2• 13 years ago

Would be great to see some solutions.

pak3• 13 years ago

It's problems like 5 that make me sad that IE <9 doesn't have Array.prototype.reduce.

    return i.reduce(function(prev, next) {
        if (typeof(next) == "object" && next.length) { return arraySum(next) + prev; }
        if (typeof(next) == "number") { return next + prev; }
        return prev;
    }, 0);

Something that simple needs to be shimmed on earlier IEs. In fact, I had to look up Array.prototype.reduce for this since I usually use Underscore's. Javascript problems...

dmak4• 13 years ago

Pretty interesting solution. The first thing that came to my head was a loop, but you just used reduce. What are some scenarios where you would use a reduce over a loop? I use underscore a lot too, and I find myself just using _.each all the time

pak3• 13 years ago

Anytime where you are trying to "collect" features of an array into one final value, and the collection function can be sensibly applied to the elements in any order as long as some interim value is passed along (e.g. summing, maximizing), the reduce paradigm is appropriate and can be more readable.

The bonus upside is that these paradigms also make parallelism quite simple, should it later be necessary.

1wheel• 13 years ago

https://github.com/kriskowal/es5-shim

pak3• 13 years ago

Cool project, but all the warnings on that page about the edge cases make me concerned about trying to exuberantly move to ES5, and so I just stick with Underscore and the same level of JavaScript syntax I've been writing since 2005. (sigh)

ianstallings• 13 years ago

I'm a bit disappointed that it doesn't award points for my heavy use of regex and obscure variable names.

Cyranix• 13 years ago

obscure variable names

Absolutely! Being under the gun led me, at one point, to have a "longest string in array" method with a statement like

  if (i[z].length < qq) { ... }

chudi• 13 years ago

nice stuff but this is plain wrong! // return the file extension (with no period) if it has one, otherwise false

its like returning error codes in C for errors

jamesroseman2• 13 years ago

I too shuddered at this instruction...

ep1034• 13 years ago

Or for using i as your input variable

dmak4• 13 years ago

I got 11 minutes and 14 seconds. Is that slow? The answer to my last solution was like this:

      function arraySum(i) {
	var total = 0
	for(var x=0; x < i.length; x++) {
		if(typeof i[x] == 'object') {
			 arraySum(i[x])
		} else if(typeof i[x] == 'number') {
			total += i[x]
		}
	}
	return total
     }

lighthazard• 13 years ago

~6 minutes and 30 seconds

That was also my final answer. However, I was going for speed and not elegance, after looking at other people's responses with prototypes and all.

dclowd99015• 13 years ago

You must've total+= arraySum(i[x]) right? Otherwise this couldn't work as the result of a deep dive wouldn't be utilized anywhere...

dmak4• 13 years ago

Yeah, I did, thanks for pointing that out. I made that mistake when writing the comment.

ep1034• 13 years ago

you made the same mistake I did at first. Corrected below.

function arraySum(i) { var total = 0 for(var x=0; x < i.length; x++) { if(typeof i[x] == 'object') { total += arraySum(i[x]) } else if(typeof i[x] == 'number') { total += i[x] } } return total }

jamesroseman2• 13 years ago

9:10, had to Google a bit for type checking, and I had forgotten the proper syntax for a string split. :-/

peregrine• 13 years ago

Total bait and switch. As soon as I saw that random array in my array of strings I knew what kind of game this would be.

metaphorm• 13 years ago

there's a truly dubious test case in the File Extension test.

file called .htaccess is not filename "" and extension "htaccess" with a "." separating the two. .htaccess is a unix style dotfile. its whole name is ".htaccess" and it has no file extension.

taternuts2• 13 years ago

I have to admit to cheating and putting 'if (i === '.htaccess') return 'htaccess';' to save time :)

jrawlings• 13 years ago

I just did

return i.indexOf('.') > -1 ? i.substring(i.indexOf('.')+1) : false;

Seemed to pass all test cases

drdrxp• 13 years ago

The input argument name "i" is really annoying. I always use "i" as for-loop var. Made some mistake on this. But the Game is really great. :D

jenjem• 13 years ago

I took almost 40 minutes, am I in the wrong profession? I figured out how to do all of them right away but I got stuck on figuring out JS syntax in a few places since I barely ever use it and felt like googling was cheating. I did use google on the last one to see how to check if something's an array. I even ended up checking at one point if something's a number by (!isNaN(n/4) && n+n == 2*n), and checked for being a string or not with if(s.length!=undefined) (I know that returns true for an array as well). Would've been a lot easier with something like Intellisense - coding without it feels almost like I'm blind, after being used to it. That and I thought alert() didn't work until I noticed at the end it actually sent it to the output.

hcarvalhoalves• 13 years ago

Last one reminded me how awful JS is once again. There are 5 different ways to check if an object is an array, some are implementation dependent, and the obvious one doesn't work (typeof x == "array").

hayksaakian2• 13 years ago

typeof(x) === typeof(["something which is certainly", "an array"])

or am i missing something?

wging• 13 years ago

     > typeof ["a", "b"]

    "object"

Of course, since you're told you'll only get numbers, arrays, and strings, that is enough to solve the problem narrowly.

Bahamut3• 13 years ago

x instanceof Array

salehenrahman2• 13 years ago

I got 3 minutes 39 seconds.

I used i.forEach for questions involving arrays, instead of for-loops. Saves me time.

salehenrahman2• 13 years ago

I created a CoffeeScript version of it. http://shovon.github.io/youcantcoffeescriptunderpressure/

You Can't JavaScript Under Pressure

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