whatsapp - show number in title.js

// ==UserScript==
// @name        whatsapp - show number in title
// @namespace   Violentmonkey Scripts
// @match       https://web.whatsapp.com/
// @grant       none
// @version     1.0
// @author      -
// @description 8.12.2023, 17:17:41
// ==/UserScript==


const debounce = (func, wait, immediate) => {
    let timeout;
    return function() {
        const context = this, args = arguments;
        const later = function() {
            timeout = null;
            if (!immediate) func.apply(context, args);
        };
        const callNow = immediate && !timeout;
        clearTimeout(timeout);
        timeout = setTimeout(later, wait);
        if (callNow) func.apply(context, args);
    };
};


(() => {

    setTimeout(() => {
        const newTitle = document.createElement("title");
        const newContent = document.createTextNode("Telegram");
        newTitle.appendChild(newContent);
        document.head.appendChild(newTitle);
    }, 1000);

    const action = debounce(() => {
        const number = document.querySelectorAll('[role="gridcell"] span[aria-label="Ungelesen"]').length;
        let title = 'WhatsApp Web'
        if (number) {
            title = `${title} (${number})`
        }
        document.querySelectorAll('title').forEach(el => el.innerHTML = title);
    }, 100, true);

    const mo = new MutationObserver(action)

    mo.observe( document, { childList:true, subtree:true })
})();