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/*--- 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; | |
} |
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).
That's good, @CoeJoder. You might also consider one of the other forks (almost 100 on Gist alone) that uses MutationObserver
.
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).
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?
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
@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:
- have you reported all my YT scripts?
- 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.
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.
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.
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.
@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.
@FRex,
You're welcome; glad the script is useful to others.
I want to paste it inside my UserScript file but I got errors like $
is not defined
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
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);
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.
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).
@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"});}
@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 - 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"});}
@BrockA would you mind to make a typescript version?
@peanutive00 Show me how to use Typescript with Tampermonkey or Violentmonkey -- in Firefox -- and I will consider it.
@BrockA I am using vite-plugin-monkey this package to do the hmr deployment in Chrome, I never tested in Firefox.
@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.
@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.
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')");
});});
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')");
}
Thank you.
This code is so bad. It should be using a MutationObserver or DOM/script load events instead of running a jQuery selector on the entire document every 300 ms.
@cow1337killer3 by all means, rewrite it :)
@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.