waitForKeyElements no jquery dependency

waitForKeyElements.js

/*--- 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 = document.querySelectorAll(selectorTxt);
    } else {
        const iframe = document.querySelector(iframeSelector);
        if (iframe) {
            const iframeDocument = iframe.contentDocument || iframe.contentWindow.document;
            targetNodes = iframeDocument.querySelectorAll(selectorTxt);
        }
    }
    
    if (targetNodes && targetNodes.length > 0) {
        btargetsFound = true;
        /*--- Found target node(s).  Go through each and act if they
            are new.
        */
        targetNodes.forEach(function (node) {
            var alreadyFound = node.dataset.alreadyFound === "true";

            if (!alreadyFound) {
                //--- Call the payload function.
                var cancelFound = actionFunction(node);
                if (cancelFound)
                    btargetsFound = false;
                else
                    node.dataset.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;
}