Allgemeine Frage(n) zu JavaScript

// userChrome.js
userChrome.ignoreCache = true;
userChrome.import("*", "UChrm");
userChrome.import("/js/Addons-UpDate-Check.uc.js", "UChrm");
userChrome.import("/js/Button-PersonalToolbar.uc.js", "UChrm");
userChrome.import("/js/Browser-Werkzeuge.us.js", "UChrm");
userChrome.import("/js/Clock.us.js", "UChrm");
userChrome.import("/js/Downloadbutton.uc.js", "UChrm");
userChrome.import("/js/FavIconInUrlBar.uc.js", "UChrm");
userChrome.import("/js/Fenster_schließen.us.js", "UChrm");
userChrome.import("/js/Hamburger-Menu.uc.js", "UChrm");
userChrome.import("/js/QuickLinkButton.uc.js", "UChrm");
userChrome.import("/js/QuickLinkButton-about.uc.js", "UChrm");
userChrome.import("/js/QuickLinkButton-cf.uc.js", "UChrm");
userChrome.import("/js/Restart_Firefox.uc.js", "UChrm");
userChrome.import("/js/Scrollbar.uc.js", "UChrm");
userChrome.import("/js/Symbole.us.js", "UChrm");
userChrome.import("/js/Translate_DeepL.uc.js", "UChrm");
userChrome.import("/js/Werkzeuge-fuer-Webentwickler.us.js", "UChrm");

(function() {

        if (location.href !== AppConstants.BROWSER_CHROME_URL) return;
        try {
           CustomizableUI.createWidget({
              id: 'bookmark-button',
              type: 'custom',
              defaultArea: CustomizableUI.AREA_NAVBAR,
              onBuild: function(aDocument) {         
                 let toolbaritem = aDocument.createElementNS('http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul', 'toolbarbutton');

                 toolbaritem.onclick = event => onClick(event);
                 var props = {
                    id: 'bookmark-button',
                    class: 'toolbarbutton-1 chromeclass-toolbar-additional',
                    removable: 'true',
                    label: 'Bookmarks',
                    accesskey: '',
                    tooltiptext: 'Bookmarks',

                    style: 'list-style-image: url("chrome://global/skin/icons/folder.svg");',
                };            
                for (var p in props)
                   toolbaritem.setAttribute(p, props[p]);            
                return toolbaritem; 
             }    
          });
       } catch(e) { };  

       setTimeout(function() { 
        document.getElementById('ucjs_PanelUI-button').appendChild(menuButton);       
        menuButton.setAttribute('consumeanchor', 'ucjs_PanelUI-button');     
       }, 0);
}) ();

/*
 * userChromeJS
 *
 * The file userChrome.js can be used to customize the functioning of Mozilla's
 * user interface. Usage and syntax follow below; for useful code snippets see
 * http://mozilla.zeniko.ch/userchrome.js.html.
 *
 * Examples:
 * setTimeout(function() { document.title = "A new title for every window" }, 2000);
 *
 * if (location == "chrome://browser/content/browser.xul") {
 *   alert("Script loaded in main browser only");
 * }
 *
 * // DOMi window
 * if (location == "chrome://inspector/content/inspector.xul") {
 *    // Move Urlbar box to main toolbar
 *    var tb = document.getElementById('bxURLBar');
 *    var el = document.getElementById('mbrInspectorMain');
 *    if (tb && el) el.appendChild(tb, el.firstChild);
 * }
 *
 * NOTE:
 * userChromeJS includes an 'import' function to facilitate file management.
 * An absolute path or relative path with Directory name property token can be
 * used, as follows:
 *
 * // Single file (javascript .js or overlay .xul file)
 * userChrome.import("Full file path");
 * userChrome.import("Relative file path", "Token");
 * // All .js and .xul files in a folder will be loaded.
 * userChrome.import("Full file folder path");
 * userChrome.import("Relative file folder path/name", "Token");
 * userChrome.import("*", "Token");
 *
 * NOTE:
 * Absolute windows files and folders must be have backslash escaped:
 * "C:\\Program Files\\Mozilla\\scripts\\myscript.js"
 *
 * Examples:
 * // Import script in [ProfileDir]/chrome/scripts/myscript.js
 * userChrome.import("scripts/myscript.js", "UChrm");
 * // Import script in [Profiles]/scripts/myscript.js (share same script in
 * // multiple profiles
 * userChrome.import("scripts/myscript.js", "DefProfRt");
 * // All .js or .xul in profile chrome directory
 * userChrome.import("*", "UChrm");
 * // Import overlay
 * userChrome.import("C:\\Program Files\\Mozilla\\scripts\\myOverlay.xul");
 * // Import everything in Desktop folder /scripts
 * userChrome.import("scripts", "Desk");
 * // Perhaps the only thing you need in this file..
 * if (location == "chrome://browser/content/browser.xul") {
 *  userChrome.import("scripts", "DefProfRt");
 * }
 *
 * NOTE:
 * For a full listing of directory tokens see the two links found here:
 * https://developer.mozilla.org/en-US/Add-ons/Code_snippets/File_I_O#Getting_files_in_special_directories
 * // What's the path for a token? This will print it in the console.
 * userChrome.log(userChrome.getAbsoluteFile("Desk").path, "getAbsoluteFile:'Desk'");
 *
 * NOTE:
 * userChromeJS includes a log function, invoked as follows:
 * userChrome.log("string1"[, "string2"])
 * Example:
 * userChrome.log("hello world!", "myscript.js");
 * Results in a console message:
 * 2009-05-22 18:07:40 userChromeJS myscript.js: hello world!
 *
 * NOTE:
 * The date format for the userChrome.log console logger may be user defined:
 * Example:
 * userChrome.dateFormat = "%Y-%m-%d %H:%M:%S";
 *
 * NOTE:
 * The default charSet is "UTF-8"; for code using the 'import' or
 * 'importFolder' functions to manage files, the charSet for subscript loader
 * may be user defined, prior to calling the import or importFolder functions:
 * Example:
 * userChrome.charSet = "UTF-8";
 *
 * NOTE:
 * Scripts are stored in a startup cache and loaded from it.
 * After a change in userChrome.js you heve to restart Firefox with clearing
 * this cache to make sure the changed file is read.
 * By default this applies to imported .js files too. You can bypass the cache
 * for these scripts with this statement BEFORE any import statement:
 * userChrome.ignoreCache = true;
 *
 */

userChrome.ignoreCache = true;
userChrome.import("*", "UChrm");
userChrome.import("scripts/Addons-UpDate-Check.uc.js", "UChrm");
userChrome.import("scripts/Browser-Werkzeuge.us.js", "UChrm");
userChrome.import("scripts/Button-PersonalToolbar.uc.js", "UChrm");
userChrome.import("scripts/Clock.us.js", "UChrm");
userChrome.import("scripts/Downloadbutton.uc.js", "UChrm");
userChrome.import("scripts/FavIconInUrlBar.uc.js", "UChrm");
userChrome.import("scripts/Fenster_schließen.us.js", "UChrm");
userChrome.import("scripts/Hamburger-Menu.uc.js", "UChrm");
userChrome.import("scripts/QuickLinkButton.uc.js", "UChrm");
userChrome.import("scripts/QuickLinkButton-about.uc.js", "UChrm");
userChrome.import("scripts/QuickLinkButton-cf.uc.js", "UChrm");
userChrome.import("scripts/Restart_Firefox.uc.js", "UChrm");
userChrome.import("scripts/Scrollbar.uc.js", "UChrm");
userChrome.import("scripts/Symbole.us.js", "UChrm");
userChrome.import("scripts/Translate_DeepL.uc.js", "UChrm");
userChrome.import("scripts/Werkzeuge-fuer-Webentwickler.us.js", "UChrm");