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A utility function, for Greasemonkey scripts, that detects and handles AJAXed content.
/*--- waitForKeyElements(): A utility function, for Greasemonkey scripts,
that detects and handles AJAXed content.
Usage example:
waitForKeyElements (
"div.comments"
, commentCallbackFunction
);
//--- Page-specific function to do what we want when the node is found.
function commentCallbackFunction (jNode) {
jNode.text ("This comment changed by waitForKeyElements().");
}
IMPORTANT: This function requires your script to have loaded jQuery.
*/
function waitForKeyElements (
selectorTxt, /* Required: The jQuery selector string that
specifies the desired element(s).
*/
actionFunction, /* Required: The code to run when elements are
found. It is passed a jNode to the matched
element.
*/
bWaitOnce, /* Optional: If false, will continue to scan for
new elements even after the first match is
found.
*/
iframeSelector /* Optional: If set, identifies the iframe to
search.
*/
) {
var targetNodes, btargetsFound;
if (typeof iframeSelector == "undefined")
targetNodes = $(selectorTxt);
else
targetNodes = $(iframeSelector).contents ()
.find (selectorTxt);
if (targetNodes && targetNodes.length > 0) {
btargetsFound = true;
/*--- Found target node(s). Go through each and act if they
are new.
*/
targetNodes.each ( function () {
var jThis = $(this);
var alreadyFound = jThis.data ('alreadyFound') || false;
if (!alreadyFound) {
//--- Call the payload function.
var cancelFound = actionFunction (jThis);
if (cancelFound)
btargetsFound = false;
else
jThis.data ('alreadyFound', true);
}
} );
}
else {
btargetsFound = false;
}
//--- Get the timer-control variable for this selector.
var controlObj = waitForKeyElements.controlObj || {};
var controlKey = selectorTxt.replace (/[^\w]/g, "_");
var timeControl = controlObj [controlKey];
//--- Now set or clear the timer as appropriate.
if (btargetsFound && bWaitOnce && timeControl) {
//--- The only condition where we need to clear the timer.
clearInterval (timeControl);
delete controlObj [controlKey]
}
else {
//--- Set a timer, if needed.
if ( ! timeControl) {
timeControl = setInterval ( function () {
waitForKeyElements ( selectorTxt,
actionFunction,
bWaitOnce,
iframeSelector
);
},
300
);
controlObj [controlKey] = timeControl;
}
}
waitForKeyElements.controlObj = controlObj;
}
@panayot-zhi
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panayot-zhi commented Mar 23, 2016

Seems the unacredited version is mine, fixed now, Cheers :)

@GollyJer You could also import this script as a resource, like this :
// @resource waitForKeyElements https://gist.githubusercontent.com/BrockA/2625891/raw/9c97aa67ff9c5d56be34a55ad6c18a314e5eb548/waitForKeyElements.js

then read it with GM_getResourceText("waitForKeyElements ") and inject it on page or eval it in script.

@terabyte
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terabyte commented Oct 4, 2016

@BrockA - Apparently github is delivering notifications 11 months delayed? wtf... Anyways, many thanks for chiming in! I might still like to use it but I don't maintain disapproval plugin much these days, so not sure if I will ever get to it. Thanks for contributing to the hive mind just the same! =D

@GollyJer
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GollyJer commented Nov 14, 2016

Thanks for that @panayot-zhi Updated my script to point directly at the gist.
https://greasyfork.org/en/scripts/13968-gollyjer-s-auto-expand-google-search-tools

@doyousketch2
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doyousketch2 commented Jan 2, 2017

@panayot-zhi - Even better yet, run the address through Git.io to get a shortened URL.
// @require https://git.io/vMmuf
Then use function normally.

@hellonearthis
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hellonearthis commented Jan 9, 2017

@mjblay
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mjblay commented Mar 12, 2018

Not sure if this has already been accomplished, but I couldn't find an example of this without the need for JQuery. I forked this and removed reliance on JQuery, though I had to hobble it by disabling the iframe search. Might help some though, and it works for my project. Thanks for your work @BrockA

@insanid
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insanid commented Mar 13, 2018

@mjblay What a crazy coincidence. I have been re-writing it as well within this past week to no longer rely on jQuery, and I also ended up removing the iframe feature until I had more time to re-write that part in vanillajs. I had published a gist a couple of days ago, but I removed it after encountering a few bugs. I checked out your Gist/Github account and couldn't find the fork. Are you planning on publishing it on Github?

@BrockA
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BrockA commented Mar 13, 2018

@mjblay, you're welcome.

@mjblay
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mjblay commented Mar 13, 2018

@insanid I inadvertently deleted it. I re-added the fork here: https://gist.github.com/mjblay/18d34d861e981b7785e407c3b443b99b. I haven't tested it thoroughly, but it seems to be working on a private site I maintain and use daily.

@Gallion
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Gallion commented Sep 17, 2018

Can this act within an iframe that is itself within an iframe?

@BrockA
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BrockA commented Sep 17, 2018

@Gallion, not directly but it can help. If you need to, open a question about that on some place like Stack Overflow and give details and a working test case or link to the target page.

@EliezerWu
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EliezerWu commented Dec 12, 2018

It's a very useful script but recently I met an issue. If waitForKeyElements already finds the element at the first run and the element disappears. The timer cannot be cleared since the element is not found anymore.

@BrockA
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BrockA commented Dec 12, 2018

@EliezerWu, Even when you set bWaitOnce to true?
Also, letting the timer keep running is not normally a problem.

Anyway, post a "Minimal, Complete, and Verifiable example" if you want me to investigate this further.

@josepelupi
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josepelupi commented Aug 12, 2019

@BrockA,

I don't know if you still want/need this, but I consider it:

Creative Commons, Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)

I'm not going to lawyer-up in any case.

Hi =)
How can i do for commercial use?
It would be used to dynamically generate buttons with javascript codes to automate tasks in my work =)

thanks.

@BrockA
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BrockA commented Aug 12, 2019

@josepelupi, And anyone else who wants to use this commercially...

Consider this free to use commercially until your install base exceeds twenty-thousand users. At which point, any fee would probably consist of a modest (3 digits or less) donation to EFF or similar.

You could add a comment to your code: "Used by permission of github.com/BrockA until install base exceeds twenty-thousand users."

How can i do for commercial use?
It would be used to dynamically generate buttons with javascript codes to automate tasks in my work =)

@josepelupi
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josepelupi commented Aug 17, 2019

@BrockA,

Many thanks for the reply. But i believe i was not clear enough in my question.

I have no intention of creating scripts to sell.

Im creating a script to share with my co-workers that automates parts of the activities we exercise while working (eg select options from a dropdown menu, fill out forms). So, my intention is to use waitForKeyElements to facilitate and allow the creation of dynamic buttons according to the elements that exist on the page.

So, i would like to know if it is allowed to include your code in my greasemonkey script to use it , "indirectly", for the purpose of commercial use.

thanks =)

Consider this free to use commercially until your install base exceeds twenty-thousand users. At which point, any fee would probably consist of a modest (3 digits or less) donation to EFF or similar.

@BrockA
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BrockA commented Aug 17, 2019

@josepelupi, I did understand you. What you propose is still commercial use. If you get 20K people who use this, then let me know and we'll hash out a tiny donation, not to exceed $100, unless you cause me to incur costs in time or money.

But, I might suggest that if your script does approach 20K users, then some intranet team has not done their job well.

Until you get 20K people using the script, just comment in the code that you are legally covered.

@CoeJoder
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CoeJoder commented May 2, 2020

This is a great script! I have modified it with what I feel are some important improvements (not requiring jQuery, not using setInterval(), allowing a selector function instead of a string).

@BrockA
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BrockA commented May 2, 2020

That's good, @CoeJoder. You might also consider one of the other forks (almost 100 on Gist alone) that uses MutationObserver.

@CoeJoder
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CoeJoder commented May 3, 2020

Yes, there are some quite fancy implementations among the forks. I would personally avoid using MutationObserver unless needed, and also wanted to get the script into a regular github repo so it can be used with common CDNs (for some reason they tend not to work with gists).

@Hydra9268
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Hydra9268 commented Mar 17, 2021

I want to move the function into an object in a separate file that I call libraries.js. The object is called singleton as in

singleton.waitForTargetElements()

However, it throws an undefined error for waitForTargetElements at this line:

let controlObj = waitForTargetElements.controlObj || {};

If I add waitForTargetElements to the list of parameters, then controlObj throws an undefined error.

So my question is how do I decouple the scope so that the function can be placed in another file but can still be called?

@Harfho
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Harfho commented Jun 10, 2021

This is a great script! I have modified it with what I feel are some important improvements (not requiring jQuery, not using setInterval(), allowing a selector function instead of a string).

THANKS EXACTALY WHAT I NEEDED.
BrockA Version , doesn't work when userscript //@run-at is set to document-start

@FRex
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FRex commented Oct 17, 2021

@BrockA I have a few scripts that modify YouTube and I use your function to detect new elements. They are small, non-commercial and have around 200-300 installs each.

Today they were all reported on GreasyFork as "unauthorized copy of https://gist.github.com/BrockA/2625891" with description being: "On 10 Nov 2015, the original author said that the license is Creative Commons, Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)."

I didn't know you can @include a git io link so all of my scripts have a verbatim copy of yours at the bottom (I'd probably prefer to do that even if I knew, in case you ever took the gist down), with phrase "From: https://git.io/vMmuf" added in the top comment describing what they are. This is how the top two lines of your code look after this addition:

/*--- waitForKeyElements():  A utility function, for Greasemonkey scripts,
    that detects and handles AJAXed content. From: https://git.io/vMmuf

My questions:

  1. have you reported all my YT scripts?
  2. are you okay or not with this usage (copy paste + link to your gist)?

I've decided not to wait anymore and submitted a rebuttal to all the reports saying you didn't ever mind or report small, non-commercial and credited use or forks on GreasyFork when learning of them in the past and that my script is small, non-commercial and links to your gist. Please confirm that this is okay with you.

@FRex
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FRex commented Oct 17, 2021

All my scripts that used this gist were were deleted by a moderator. The message I've received:

I consider https://gist.github.com/BrockA/2625891#gistcomment-1617026 the most clear statement by the author. Please comply with the terms of that license.

@BrockA
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BrockA commented Oct 17, 2021

@FRex,

That wasn't me and I don't see how it applies to you, unless you are somehow selling your scripts.

I wonder if it was a YT bot; they're really going sick over there.

Anywho, I have now released this utility to the public domain.

@FRex
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FRex commented Oct 17, 2021

Thank you for the help. I've submitted even more appeals. I will update here if they are accepted or rejected. I will also make a complaint about this on GreasyFork forum.

I wonder if it was a YT bot; they're really going sick over there.

I don't know what a YT bot means in this context. The reports all linked to your comment about CC-BY-SA-NC and it was upheld by a GreasyFork moderator who ignored my wall of text about how you didn't disapprove/attack copies and forks of your gist.

@FRex
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FRex commented Oct 17, 2021

@BrockA my scripts were all restored. I have no further issues.

Thank you again for your quick reply, the CC0 relicensing and the original function.

@BrockA
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BrockA commented Oct 17, 2021

@FRex,
You're welcome; glad the script is useful to others.

@SalimF
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SalimF commented Jun 10, 2022

I want to paste it inside my UserScript file but I got errors like $ is not defined

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