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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 (
, 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
bWaitOnce, /* Optional: If false, will continue to scan for
new elements even after the first match is
iframeSelector /* Optional: If set, identifies the iframe to
) {
var targetNodes, btargetsFound;
if (typeof iframeSelector == "undefined")
targetNodes = $(selectorTxt);
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 = ('alreadyFound') || false;
if (!alreadyFound) {
//--- Call the payload function.
var cancelFound = actionFunction (jThis);
if (cancelFound)
btargetsFound = false;
else ('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,
controlObj [controlKey] = timeControl;
waitForKeyElements.controlObj = controlObj;

@BrockA : could we please get this under a BSD or Apache 2.0, or some other compatible license? We'd like to include it in which is apache 2.0.


(also, either way, deep gratitude for writing it!)


Something's wrong with current Firefox, the script just stops on targetNodes.each(). Still works on SeaMonkey or older Firefox, so it's not just me or the page I'm working with, or is it?

What I did was:

-        targetNodes.each ( function () {
-            var jThis        = $(this);
+        for (var i = 0; i < targetNodes.length; i++) {
+            var jThis        = $(targetNodes[i]);

And looks like it works, but I'm not sure if I'm not making some type-casting crime or whatever ;)


It fails to work when other javascript framework use $() as alias. So it's better to use jQuery() explicitly.
You can get update from my fork


Huh, I've not been getting email alerts for this? But GitHub seems to email just fine.


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.


Hey Brock. Thanks for your help over on StackOverflow!
I'm looking to post my greasemonkey script on GreasyFork and it @includes waitForKeyElements. However, GreasyFork doesn't allow includes of GitHub scripts by default and someone else is hosting a version of your script on GreasyFork.

GreasyFork has Github sync functionality.

A GitHub webhook connected with Greasy Fork makes it so any push to your GitHub repository automatically updates your scripts on Greasy Fork in a matter of minutes.

I'd love to @include your script instead of a copy. If you aren't interested in creating a GreasyFork account let me know and I'll use the already posted script. Otherwise, point me to the GreasyFork version.



@GollyJer, Interesting, there appear to be at least 4 copies of waitForKeyElements on Greasy Fork:

3 out of 4 of them even credit me; I can die in peace! :D

Anywho, I've no interest in creating a Greasy Fork account at this time. Use whichever version/method that works best for you.

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