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@BrockA
Created May 7, 2012 04:21
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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;
}
@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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@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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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

@hooy
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hooy commented Oct 30, 2022

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

You need jquery to be installed, e.g.
// @require https://code.jquery.com/jquery-latest.min.js

Or you can use version provided by CoeJoder https://gist.github.com/BrockA/2625891?permalink_comment_id=3279773#gistcomment-3279773

@Hydra9268
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Hydra9268 commented Oct 30, 2022

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

You could do something like this:

// Loads jQuery and triggers a callback function when jQuery has finished loading
function addJQuery(callback) {
    let script = document.createElement('script');
    script.setAttribute('src', '//code.jquery.com/jquery-latest.min.js');
    script.addEventListener('load', function() { callback(); }, false);
    document.body.appendChild(script);
}
 
// The main script
function main() {
 // YOUR CODE GOES HERE
}
 
// Load jQuery and then execute the main function
addJQuery(main);

@enchained
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Is it possible to make waitForKeyElements work with async calls at intervals?

I use waitForKeyElements on a page with paginated lists, with list element as the selector. In my userscript, I have a function that returns a promise after making GM_xmlhttpRequest and fetching some data. I need to run it at sparse intervals to be gentle with the api. But if I use waitForKeyElements on a class corresponding to multiple elements, requests go all at once. I tried using async/await and setTimeout inside my callback function, but I couldn't get the desired results. Is this somehow possible?

I know that async functions do not properly work with forEach() loop, but work with for/of. But in this case I need something like waitForKeyElements to detect that items updated after a pagination.

@BrockA
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BrockA commented Dec 8, 2022

@enchained,

Yes, that is possible. It sounds as if you are calling the API from within WFKE and it's spamming the server?

In that case, maybe you can use a different selector that only changes once per page? If not, wrap debouncing techniques around the API call. Something like https://www.freecodecamp.org/news/javascript-debounce-example/

Also, depending on your situation, WFKE may not be the best choice. Don't be afraid to just use a plain old setInterval or MutationObserver.

Can't help much more without details but this is not the place for that. (Unless you have a very short MCVE).

@gaveitatry2
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gaveitatry2 commented Oct 7, 2023

@BrockA - Thank you for this waitForKeyElements script. I was making user scripts by trial and error and sometimes my code didn't work and someone suggested using this script and it made my code work. So most of the time I use waitForKeyElements for everything.

There is only one problem though. It won't let me add !important. The following won't work. I have to remove the !important part for it to work, and I often do need the !Important on some elements and websites.

waitForKeyElements ("ELEMENT", Example);
function Example (jNode) {jNode.css({"border-radius" : "24px !important"});}

@BrockA
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BrockA commented Oct 7, 2023

@gaveitatry2 - I'm glad the script is useful to you.

But that CSS thing is a quirk of jQuery. You need to adjust your code slightly.
See https://stackoverflow.com/a/11963008 for how to set the !important flag.

@gaveitatry2
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gaveitatry2 commented Oct 7, 2023

@gaveitatry2 - I'm glad the script is useful to you.

But that CSS thing is a quirk of jQuery. You need to adjust your code slightly. See https://stackoverflow.com/a/11963008 for how to set the !important flag.

Thank you so much! This is a problem that I have had for many years, and I never knew that there was a solution!

I changed this (doesn't work):

waitForKeyElements ("ELEMENT", Example);
function Example (jNode) {jNode.css({"border-radius" : "24px !important"});}

To this. And now it works:

waitForKeyElements ("ELEMENT", Example);
function Example (jNode) {jNode.attr("style", "border-radius: 24px! important").css({"SOME OTHER CSS"});}

@peanutive00
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@BrockA would you mind to make a typescript version?

@BrockA
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BrockA commented Oct 30, 2023

@peanutive00 Show me how to use Typescript with Tampermonkey or Violentmonkey -- in Firefox -- and I will consider it.

@peanutive00
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@BrockA I am using vite-plugin-monkey this package to do the hmr deployment in Chrome, I never tested in Firefox.

@CoeJoder
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CoeJoder commented Nov 1, 2023

@peanutive00 If you're just trying to benefit from static typing while using this script as a dependency in a TypeScript project, you only need to have the JavaScript annotated with JSDoc type hints. See JSDoc Reference for TypeScript. For example, see my fork of this script. Or, you could produce a .d.ts file for the original version and avoid modifying the .js file altogether.

@BrockA
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BrockA commented Nov 1, 2023

@peanutive00 Thanks, I'll check that out but I don't do much TM coding these days so it may be a long while. Meanwhile CoeJoder seems to have a workaround.

@gaveitatry2
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gaveitatry2 commented Jan 8, 2024

@BrockA

Could you convert the following code into waitForKeyElements, please? When I use it as is, it only works on some of the span.rightActionButton elements on each page, but not all of them. So I want to see if it will work if I use wFKE, but I don't know the proper format. Hope you don't mind. Thanks.

$(document).ready(function(){
$('span.rightActionButton').each(function(){
$(this).css("background-color", "red");
var oldUrl = $(this).attr("onclick");
var newUrl = oldUrl.replace("window.location='", "window.open('https://www.somewebsite.com");
$(this).attr("onclick", newUrl + ", target='_blank')");
});});

@BrockA
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BrockA commented Jan 8, 2024

@gaveitatry2 ,

That entire code block would be replaced with:

waitForKeyElements ("span.rightActionButton", rewriteSpanLinks);

function rewriteSpanLinks (jNode) {
    jNode.css ("background-color", "red");
    var oldUrl = jNode.attr ("onclick");
    var newUrl = oldUrl.replace ("window.location='", "window.open('https://www.somewebsite.com");
    jNode.attr ("onclick", newUrl + ", target='_blank')");
}

@gaveitatry2
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Thank you.

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