Anon-chat YT script

// ==UserScript==
// @name        LiveChat - youtube.com
// @namespace   Violentmonkey Scripts
// @match       https://*.youtube.com/live_chat*
// @grant       none
// @version     1.0
// @author      -
// @description 12:39:32 AM
// ==/UserScript==

function waitForElm(selector) {
    return new Promise(resolve => {
        if (document.querySelector(selector)) {
            return resolve(document.querySelector(selector));
        }

        const observer = new MutationObserver(mutations => {
            if (document.querySelector(selector)) {
                resolve(document.querySelector(selector));
                observer.disconnect();
            }
        });

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

waitForElm("#author-name").then((elm) => {
    console.log('Element #content is ready');
    elm.textContent = "Anon";
});

function getElementByXpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}

liveChat = document.getElementById("live-chat-message-input").style;
console.log(liveChat);

userName = getElementByXpath("/html/body/yt-live-chat-app/div/yt-live-chat-renderer/iron-pages/div/div[1]/iron-pages/div[1]/yt-live-chat-message-input-renderer/div[1]/div[1]/div/yt-live-chat-author-chip");
console.log(userName);
userName.innerText = "Anon.";
userName.style.visibility='hidden';

userChat = getElementByXpath("/html/body/yt-live-chat-app/div/yt-live-chat-renderer/iron-pages/div/div[1]/iron-pages/div[1]/yt-live-chat-message-input-renderer/div[1]/div[1]/div/yt-live-chat-text-input-field-renderer/label");
console.log(userChat);
userChat.innerText = "Write something";

userImg = getElementByXpath("/html/body/yt-live-chat-app/div/yt-live-chat-renderer/iron-pages/div/div[1]/iron-pages/div[1]/yt-live-chat-message-input-renderer/div[1]/div[1]/yt-img-shadow/img");
userImg.width = 0;
userImg.height = 0;
console.log(userImg);

userLiveChat = getElementByXpath("/html/body/yt-live-chat-app/div/yt-live-chat-renderer/iron-pages/div/div[1]/iron-pages/div[1]/yt-live-chat-message-input-renderer");
userLiveChat.style = "padding:0px 16px; margin-top: -15px;"
console.log(userLiveChat);