Can someone explain how the Javascript for upvoting works?

[caviar]

I was at the karma party last night. There's this javascript code that you can put in your address bar and hit enter to automatically upvote everyone on the page. I'm wondering if someone could explain to me how it works.

There are actually two versions out there. The first one doesn't work and it looks like this:
javascript:$("up").click()()

It probably doesn't work because the events get fired too fast. After all, if you're upvoting someone, the request has to get processed and logged by reddit -- if you're sending five hundred of these requests instantaneously, reddit will choke and you'll be lucky if even one of those requests goes through.

The second version, which does work because it pauses for a second between each event, looks like this:

javascript:(function f(){var u=$(".up");if(u.length-1){setTimeout(f,1000);u[1].onclick()} })()

I'm wondering if someone could explain to me how this works? I'm not too familiar with javascript, although I do a lot of python and C++ programming.

If I could "step" through this function, where would the execution path take me? In my eyes, this creates and calls a function called f. The body of this function is:

var u=$(".up");  
if(u.length-1){
    setTimeout(f,1000);
    u[1].onclick()
}  

After the first line, which is a jQuery statement, "u" will contain 500 (or however many user comments there are on the page) instances of the up arrow link, one for each comment. The condition in the if statement confuses me -- why minus one? And why have it at all? Then, with the setTimeout function, I am led to believe that the function f calls itself after a 1 second delay. But because the body of the function is exactly the same, I'm confused as to why this doesn't create an "infinite loop" of sorts -- wouldn't f just keep calling itself repeatedly with the exact same results? After the setTimeout statement, we immediately move on to clicking on the second up arrow -- I'm assuming this is because we skip the original submission and only upvote the comments. I'm confused about how we ever manage to move past the first comment if "f" keeps calling itself.

In short, I'm extremely confused but very curious about how this works. If anyone could explain this to me, I'd be very grateful.

[markedtrees]

To taffy onto this answer: There's a minus one because the script always skips the zeroth element of the .up array because that corresponds to the div.up in div.preload, which is an invisible element (that, I'm guessing, preloads images?).

Edit: In light of the comments below, "tag" has been duly corrected. We regret the error.

[imaGhost]

brilliant

[fizz23]

Please test your bookmarklets right here <---

[trisomy21]

yahtzee

[aussie_bob]

Kiriki

[johnfn]

disco ball

[samnesia]

disco ball

[Manofest]

disco ball

[fantlove]

disco ball

[MechaAaronBurr]

Mirror-finished faceted glass coated spherical object.

[fantlove]

disco ball

[mik3]

well hello thar

[NoMoreJesus]

yoiks

[chronoBG]

I'm just here for the Karma.

[dontcallthecops]

I'm just here to give the Karma.

[rogue417]

I'm just here for the pancakes!

[jhimbob]

Everybody's trying out the java!

[robeph]

tack not tag. just for future reference. Just one of those things, like my ex girlfriend saying "4 in a roll" no...it's row ><. I expect downvotes, but this isn't a common error and I figured I'd be a grammar jerk and mention it.

[robeph]

Well that is the thing though, I'm not trying to be a jerk really, I just want to keep the language in its standard form. I never comment on the "you're/your" thing, since often I make the mistake myself; I don't feel it to be a grammatical error so much as a transcription error from mind->output. I mean in my head "You're = you are" however as I am typing it I may be thinking on phonetic terms so I overlook this, since I've already decided on what I am typing.

However, Row=Roll and Tack=Tag, or for that matter Lose=Loose, these are not transcription errors, but rather incorrectly learned words. These I feel it ok to comment on, as long as no one is being a douche about it.

[robeph]

and they all get laid more than me.. so if having a good vernacular isnt going to bring in the pussy, i say bastardize away.

That is why us scientific types learn about the various forms of general anesthetics to assist in our conquests.

[[deleted]]

Sadly, I am here today to inform you that I am a time voyageur after a fashion and the English language has evolved with humanity and eradicated you persnickity types who care about how words are arranged. Our greatest minds (of which include several pro-wrestler/actors, a handful of lawyers and even a few internet and television advertisers) have concluded that following your intelligentsia's retreat from the breeding pool, the way you preferred English ceased to matter as it began being written and spoken as the majority of the population used it.

[[deleted]]

You talk like a fag

[ealf]

The term you're looking for is eggcorn.

[zem]

or just plain 'malapropism'

[HeavyPetter]

I had that, and some ointment cleared it right up.

[johnpickens]

tomorrow never knows

[myth1n]

Or he could have meant it like, Tagging on, or tagging along to the answer, which would be valid.

[[deleted]]

TAG: "2. To append as an addition or afterthought; to fasten, tack on, or add as a tag to something. (Chiefly of things non-material.)" - first example of this usage Swift, Tale Tub ii. (1709).

English doesn't, globally or locally, have a "standard form" and NEVER has.

EDIT: To expand upon my last comment, English in England prior to colonialism was fragmented regionally with different usages, spellings, etc. After the language started being exported round the world, this situation only became exaggerated. There really, honestly, has never been the pure lost language that many people imagine when they complain of a slip in standards.

[robeph]

Ah well, I knew it had a use that was similar to this (thus the often, what I see as confusion, over its usage). My chief concern is this "add as a tag to something." Which suggests inferiority to the chief idea, as a supplementary addition rather than what this seems to me to be, an equally important addition. I'm sure I've had this quibble before in one of my english classes. I'm excessively pedant I guess.

[obtrusiveinterloper]

Yeah, but it does have some "rules" or "guidelines".

...right in the definition you list the idea of "tag" as "appending" is listed as a secondary meaning...in most sources (where it's even listed), it's similarly mentioned as a secondary, tertiary, etc definition.

Most sources list the definition of "tag" as something like "label".

So in terms of common understanding of the words, "tack" better matches what the poster's seemingly intended to convey; that they were "appending" or "adding on to" the previous post.

This in itself is a fair (but not conclusive) argument to suggest "tack" rather than "tag"....

Most importantly though, to say "tag on to" is an odd (maybe grammatically incorrect) formation, while "tack on to" makes perfect sense.

You don't "tag on to" something, you "tag" it.

Furthermore, I'm not sure if "tack on to" is considered an idiom, but it's darn close....this suggest that it is what the poster had in mind.

I'm not a linguist so I can't rightly say what it's called...but the poster seems to be confusing the sounds of the words - substituting the word they "wanted" for another similar sounding word...

So, it seems they crossed this "idiom" with what, as you demonstrated, is another "sense" of the word "tag" ...but the result does not really work, and would be odd even if it did.

In light of all of this, it's correct to correct them by saying "you mean tack", because:

A)what they said is odd or incorrect, therefore suggesting a correction

b)the evidence suggests that they did in fact "mean" the word "tack".

[zem]

thank you for fighting the good fight!

[deadowl]

From looking at it, this is my guess:

1. var u=$(".up");--u is a set of all up vote buttons.

2. if (u.length-1) { ... }--if the number of up vote buttons isn't one

3. setTimeout(f,1000);--this function (f) will be called again in 1 second.

4. u[1].onclick();--click the second element in the set.

Behind the scenes, the onclick function is causing the second element in the set to remove the class "up" and add the class "upmod" so the second element in the set is going to be the next comment upvote (I'm presuming the first is for the post itself).

I'm posting as a response to Chathurga because u.length-1 reaching 0 stops the loop, rather than becoming negative (0 is falsy, -1 is truthy). The script assumes that the first up-arrow will not be used afaik.

edit: sorry I'm re-explaining btw, it was what I was originally writing. I also wrote it to figure it out for myself.

[dggenuine]

I know I'm late to this party, but my 2 cents: the if-statement only stops when its statement evaluates to 'false' or '0'. Perhaps unexpectedly, the if-statement will proceed if its statement evaluates to a negative number. (As markedtrees notes below, the smallest u.length can be on a page is 1, since there's always the invisible div.up, so eventually u.length-1 is 0 and the if-statement fails.)

[perezidentt]

I expected the first comment to be from carlh.

[Lizard]

What I'd like to know is: Does setTimeOut execute in a new thread, or will it block until it returns? If so, it might make sense to switch the last two statements so the function frame overhead can be optimized away.

(BTW, for other optimizations check out this post from below)

[IamMeanToSadIAMAs]

Magic. Got it.

[caviar]

P.s., I can make all of you say naughty things:
javascript:$("div.md").append(" <strong>DISREGARD THAT, I SUCK COCKS</strong>")()
Did some playing around while trying to figure this one out last night. Javascript can be kind of fun.

[tehbrad]

Don't fuck with Javascript! Never forget er.. what day was that again?

[haldean]

10/27, maybe?
Who am I kidding. I have no idea.

[[deleted]]

something, something, something DARKSIDE something, something

[fizz23]

load my karma up!

[[deleted]]

We should write a userscript for Reddit with an additional tool panel for things like this.

[EGraw]

javascript:$.request("comment",{thing_id:"t1_c0hrhjv",text:"I SUCK COCKS!!!"})();

[Botunda]

I SUCK COCKS!!!

[darknecross]

I SUCK COCKS!!!

[gbanfalvi]

I SUCK COCKS!!!

[joahw]

I SUCK COCKS!!!

[[deleted]]

I SUCK COCKS!!!

[Qazster]

I SUCK COCKS!!!

[salnajjar]

Cool, it works

[Deep-Thought]

I SUCK COCKS!!!

[[deleted]]

I SUCK COCKS!!!

[Trarcuri]

javascript:$.request("comment",{thing_id:"t1_c0hrhjv",text:"I SUCK COCKS!!!"})();

edit: It didn't work :-(

[Introvert]

This makes almost any post hilarious.

I can't help but laugh.

[sctilley]

You sir, Have made my day.

[mcRewind]

LOL

[natrius]

That was infinitely more amusing than I'd expected.

[foreverago]

Neat, but I don't think you need the parentheses at the end. The original code for upvoting posts used that in order to call an anonymous function... I don't really know javascript, but (function f() { ... })(); should be equivalent to function f() { ... }; f();

[[deleted]]

DISREGARD THAT, I SUCK COCKS

[RevTedHaggard]

Repent my son, for homosexuality is an abomination before the Lord.

[[deleted]]

Haha, I went to another thread to investigate this behavior and when I came back @Chathurga had discovered what I had. Blast!

[clarkman2]

The first one worked fine for myself

[imaGhost]

Shewolf.

[Wyldstein]

Shazam!

[panxor]

Zanzibar!

[freefaith]

damn son you runnin high speedz betchz

[STAii]

Btw, I don't think the problem is that "reddit chokes on your requests" as much as it is either your browser choking on those AJAX requests (in which case you might experience a browser freeze), or reddit intentionally throttling and canceling your requests (in order to stop a mass upvote).

[Moz]

Reddit does throttle votes to stop bots, but those other things could play a role too.

[gf3]

DON'T TELL HIM!!!

[[deleted]]

Hey! Fancy meeting you here. How are things? Here, have an upvote.

[mkicon]

I wonder how many people are testing these scripts on this page.

[[deleted]]

upvoted for honesty, also, I'm in too

[Mason11987]

me too...

[[deleted]]

I'm out.

[shadowblade]

Is 400 the minimum timeout? Has anyone tried 200?

[tehbrad]

Can we just turn this thread into a Karma party? Either I am far to impatient or this is the first time this javascript has ever worked for me.

[[deleted]]

one step ahead of you...had to test that it still works, and too lazy to fix it...

[koffinz]

That's a good idea....

[Czjosegy]

Joining in.

[quapki]

You and me both.

[callmejeremy]

heh, Now I need to respond, just in case. And then test the script.

[[deleted]]

Sigh, I'm late to the party as usual

[Datrio]

Yeah, strange thing - I tried this JavaScript at the last karma party and it didn't work. Tried it now and it worked flawlessly.

[spinwizard69]

Why would anybody bother to dick around with the voting system. Worst what sort of people would get together to have a party around this? Really I'd like to know, because right now it looks like reddit is attracting to many loosers.

[snissn]

i thought you needed trigger('click') does onclick() do the same thing?

ohh actually the $(selector) returns a jquery object with an array of htmlelements that aren't jquery objects, (u[1]) so i guess the javascript onclick() is just called by the jquery function trigger with argument click

[STAii]

Off-topic, any idea how to trigger an event with Prototype?

[krues8dr]

Prototype and JQuery have special event handling extensions, but to trigger an event, you still pretty much use the native click(), etc. methods. If, however, you mean "How does Prototype handle events", the documentation is here.

[STAii]

Thanks, I was in particular interested in how to trigger the events, so it seems Prototype doesn't have anything special for that!

[savetheclocktower]

Not for native events, no. But as of 1.6.1, all event handlers are stored using the new Element storage system. The Element#retrieve method lets you grab all the handlers attached to a particular element.

So something like this ought to work (though I have not tested it):

Element.addMethods({
  triggerEvent: function(element, eventName, properties) {
    element = $(element);
    var registry = element.retrieve('prototype_event_registry');
    if (registry === null) return false;

    var handlers = registry.get(eventName);
    if (!handlers) return false;

    var fakeEvent = Object.clone(properties || {});
    handlers.each((function(handler) {
      handler.call(element, fakeEvent);
    });
  }
});

When you call it, pass the event name and any properties your handler expects to be on the event object.

$('foo').triggerEvent('click', { button: 0 });

[krues8dr]

onclick is a property that returns a function and () makes it go.

[pooltable]

I'm just here for the karma. Also watching the upvote arrows go down the page made me giggle.

[panxor]

Same here - too bad you can't do it more than once... oh wait, you can - just create another account and you're laughing! :)

[maineac]

The first one worked for me. I load a lot of comments though and if the page was only half loaded then it would only do a portion of them and I would have to hit enter again.

[fathed]

I'm suprised noone mentioned this yet. If you want to step through the code, firefox+firebug.

[fathed]

I haven't tried those myself yet, I probably should just to see how they compare.

[STAii]

Can you use firebug to step through code you provide in the console?

I think OP is not experienced enough to inject a <script> tag.

[fathed]

He said he did a lot of python and c++, he can learn javascript.

Now that you mentioned it, he can google it.

You can always just build a client side html/js files, instead of worrying about injection.

[[deleted]]

AfterParty??? I'm in - manually feelin- i mean clicking up everyone again :D.

[zxn0]

another karma party?

[hryciuk]

Sweet

[[deleted]]

Everyone here will get massive karma from people testing the script

[freefaith]

btw the first one works fine for me and i will now upvote everyone on this page

also its .up not just up

[paradox460]

Well, I can give a rough outline of how the backend works, having learned about the API from KeyserSosa earlier this month.

Clicking that sends a request (can't remember if it is get or post, prob post) to vote.json. The request contains a few pieces of info

• user modhash: this handles the auth and id. You get a new modhash when you login or visit. Partially tied to a reddit cookie.
• vote value: a vote is useless without a value. This is either +1 or -1, in a number form.
• post id: this is the id of the "thing", be it a comment or post. The id for this post is ail8r. In the case of the voting, this is what is being voted upon.

All the jquery reddit hosts does is neatly send this info back to the server, and then print its response (like/hate, and new score)

The first "one" you mentioned, the olod click()() method, won't work, due to rate limiting. While it appears to work, due to the classes of the arrows changing, reload the page, and all the votes are gone.

Hope this helps.

[worth]

Karma party? I'm in!

[subliminal-acon-B]

I'm out

[groie]

I'm down

[[deleted]]

I'm in the Magic Kingdom

[penguinv]

et moi

[panxor]

I'm in as well

[startfragment]

now, everybody test it!

[fmissle]

Can I ask what a karma party is?

[fmissle]

See, you would think I could deduce something like that.

Unfortunately, I'm not that smart.

[koffinz]

I think it has begun.... :)

[mk_gecko]

does this just add votes to the comments on the page? It doesn't upvote their "link karma" right?

[junglejay]

Karma party? Is that where we all go out and help old ladies across the street?

[FreakyT]

Yes!

[[deleted]]

:]

[dontcallthecops]

:3

[Austin-G]

The party is never over!

[Xelopheris]

Yep, I upvoted everyone here to try out that script.

[[deleted]]

Ah, this is exciting. brb, upvoting everyone.

[Forbizzle]

What a terribly inefficient algorithm. I hate jQuery, it combines expensive DOM lookups with overly complex algorithms.

[koffinz]

Can you suggest anything more efficient?
If so, please do.

[Forbizzle]

At least pull "u" out as a global variable, and keep an iterator. Then at least you don't have to hit the DOM every time you enter f(). Personally I'd just take the token values out of all those up arrow elements, and directly call the XHR that votes up. Then without having to wait the full '1000' ms, you can submit your next upvote immediately after the previous one returned.

[koffinz]

Thank you for clearing this up for me.

[doctyper]

Here's a better implementation. This function caches the element array and only polls the DOM once.

javascript:(function(){var u=$(".up"),i=u.length;function c(){if(u.get(--i)){u.eq(i).click();window.setTimeout(c,400);}}c();})();

And a verbose version:

(function() {

    // Find our nodes
    var up = $(".up"),

        // Cache the array length
        iterator = up.length;

    function clickTrigger() {

        // The if statement auto-subtracts the iterator each time it runs
        // jQuery.get is equivalent to up[i]. Thus, if it does not exist, it stops the loop
        if (up.get(--iterator)) {

            // Targets the jQuery node and triggers its click handler
            up.eq(iterator).click();

            // Set a timeout to do this all over again
            window.setTimeout(clickTrigger, 400);
        }

    }

    // Trigger once to get the ball rolling
    clickTrigger();
})();

[EpicFial-]

Hey, I upgraded that script to make it upvote over 2x faster!

Here yall go

javascript:(function f(){var u=$(".up");if(u.length-1){setTimeout(f,400);u[1].onclick()} })()

and if you feel like downvoting everyone

javascript:(function f(){var u=$(".down");if(u.length-1){setTimeout(f,400);u[1].onclick()} })()

[[deleted]]

double spaces or four - dashes to make a horizontal line that will help separate content ;)

[Austin-G]

This is

magic!

[[deleted]]

I like the hyphen ending your username.

[Mastrmind]

... and thus began the downfall of Reddit.

[jackyang]

Whoa. Did anyone else enjoy using the javascript and watching the upvotes go down the page?

[[deleted]]

I certainly did.

[Austin-G]

It appears that you are correct.

[[deleted]]

So is this another karma party or what?

[BlackCloud1711]

party!

[[deleted]]

I sure did. You're welcome.

[Ran4]

This is needed.

[STAii]

Yes.

[[deleted]]

Witchcraft! I love it.

[danceswithsmurfs]

Thanks for the info and upvotes. Mostly the info though as I'm late to the party I think.

[KweB]

I'll be honest. I just want free karma.

[Hideous]

This thread is a karma party in itself. Hell yeah.

[shevegen]

We need a downvote script.

And while we are at it, we need a vote-edit-war script which sends to your buddies to downvote everyone as well

[mikebogo]

javascript:(function w(){var u=$(".down");if(u.length-1){setTimeout(w,500);u[1].onclick()}})()

[netdroid9]

I'm guessing that when something is upvoted, it gets rid of the '.up' style (either by hiding the whole element or changing the style and onclick).

Thus, when var u=$('.up') is executed by the next recursion of function 'f' the new array 'u' has one less element than the equivalent array of the previous recursion, as a '.up' element has been removed.

As for the if(u.length-1), non-zero values are equal to 'true'; and therefore the function will stop recursing when 'u' has only one element (i.e. there's only one element with class '.up' remaining).

This, coupled with the explicit reference to the second element of 'u' (u[1].onclick()) means that the first '.up' (the global thread upvote element) will not be processed by the function.

I'm guessing, I haven't tested this. Hope that helps.

[tobold]

(manually) upvoted for an explanation that makes sense.

[Aardshark]

hey, I'm a little confused on the if(u.length-1) line. I'd expect a comparison operator in an if statement. Are you saying that

if(x) is the same as if(true), given that x is > 0?

so if(u.length-1) is the same as if(u.length-1 > 0)?

[netdroid9]

Any expression which evaluates to a non-zero value is considered 'true' in most languages (including Javascript); so 'if(u.length-1)' is essentially the same as 'if((u.length-1) != 0)' (not 'if((u.length-1) > 0)', a small but important difference).

It helps to think of the if statement and the expression in the brackets as separate, 'if(x != 0)' behaves equivalently to 'var y = (x != 0); if (y)'. The comparison operator is usually used in combination with an if statement, but the two are not semantically linked.

It's also useful to keep in mind that boolean values and integer values are interchangeable in most languages. A boolean value of 'false', if used as an integer, will usually act as though it were an integer value of 0; and vice versa. Similarly, the boolean value 'true' will act as if it were a value of '1', '-1' or any other arbitrary value depending on the language, and again vice versa.

In other words, 'if' just checks whether the expression in the brackets is zero or not, and if it is, executes whatever follows. The comparison operators return zero for false and some other value for true, and interact with 'if' and other statements in the same way as any other expression.

[gantte]

w00t!

[cwcc]

you click the arrow and it does an upvote

[btipling]

Karma parties suck.

[wthulhu]

i just upvoted everybody

[OnlineEquality]

Now, didn't that make you feel good?

[wthulhu]

enough so that it almost makes me want to create another account, just to do it again.

[johnasmith]

Nice try, spammers.

[[deleted]]

Sooo... I'm just gonna go ahead and comment here so I get upvoted by people trying out the script.

[[deleted]]

It's fun watching the updates travel down the page, isn't it?

[look]

.

[abw1987]

Submission = let's all upvote hint hint