Creating a WebSocket Listener

websocketlistener.user.js

// ==UserScript==
// @name         A Test
// @namespace    com.github
// @version      0.0.0
// @description  A Test
// @author       Scott Schreckengaust <scottschreckengaust@users.noreply.github.com>
// @match        http://*/*
// @match        https://*/*
// @grant        none
// @antifeature
// @noframes
// @sandbox      JavaScript
// @run-at       document-start
// ==/UserScript==

/* if grants below replace `none` above websocket messages aren't received */

// @grant        GM_addElement
// @grant        GM_addStyle
// @grant        GM_addValueChangeListener
// @grant        GM_cookie
// @grant        GM_deleteValue
// @grant        GM_download
// @grant        GM_getTab
// @grant        GM_getTabs
// @grant        GM_getResourceText
// @grant        GM_getResourceURL
// @grant        GM_getValue
// @grant        GM_info
// @grant        GM_listValues
// @grant        GM_log
// @grant        GM_notification
// @grant        GM_openInTab
// @grant        GM_registerMenuCommand
// @grant        GM_removeValueChangeListener
// @grant        GM_saveTab
// @grant        GM_setClipboard
// @grant        GM_setValue
// @grant        GM_unregisterMenuCommand
// @grant        GM_xmlhttpRequest
// @grant        unsafeWindow
// @grant        window.onurlchange
// @grant        window.close
// @grant        window.focus

// https://github.com/Tampermonkey/tampermonkey/issues/1961

// NOTE: Testing with Tampermonkey v5.0.1 in Chrome 120.0.6099.199 (Official Build) (arm64) on macOS 14.2.1 (23C71)

(function aTest() {
    'use strict';
    let toggled = false
    function testMenu() {
        try {
            if (typeof(GM_registerMenuCommand) === "object") {
                const menu_command_id_1 = GM_registerMenuCommand("Toggle", function(event) {
                    toggled = !toggled;
                    if (toggled) {
                        alert("On");
                    } else {
                        alert("Off");
                    }
                }, {
                    accessKey: "t",
                    autoClose: true
                });
            } else {
                console.warn("GM_registerMenuCommand doesn't exist");
            }
        } catch (testMenuError) {
            console.error(testMenuError);
        }
    }
    try {
        testMenu();
        const OriginalWebSocket = window.WebSocket;
        class UpdatedWebSocket extends OriginalWebSocket {
            constructor(url, protocols) {
                try {
                    console.debug("constructor START");
                    super(url, protocols);
                    const createEventListener = (name) => {
                        console.debug("createEventListener");
                        return (event) => {
                            try {
                                console.debug("(event) START");
                                console.info(event);
                            } catch (webSocketError) {
                                console.error(webSocketError);
                            } finally {
                                console.debug("(event) FINALLY");
                            }
                        };
                    };
                    this.addEventListener('open', createEventListener('open'));
                    this.addEventListener('close', createEventListener('close'));
                    this.addEventListener('message', createEventListener('message'));
                    this.addEventListener('error', createEventListener('error'));
                    console.debug("constructor END");
                } catch (constructorError) {
                    console.error(constructorError);
                }
            }
        }
        console.debug(window.WebSocket, "window.WebSocket (same as OriginalWebSocket)");
        window.WebSocket = UpdatedWebSocket;
        console.debug(window.WebSocket, "window.WebSocket (should be UpdatedWebSocket)");
        console.debug("SUCCESS");
    } catch (error) {
        console.error(error);
    } finally {
        console.debug("FINALLY");
    }
})();