SE chat: remove "X hours later" message

XHoursLater.js

// ==UserScript==
// @name         Remove "X Hours Later" text
// @namespace    https://_.pxeger.com/19thByte
// @version      1.1
// @description  Remove the useless "X Hours Later" message that appears on SE chat
// @author       Patrick Reader <_@pxeger.com>
// @match        https://chat.stackexchange.com/rooms/*
// @icon         https://chat.stackexchange.com/favicon.ico
// @grant        none
// @updateURL    https://gist.github.com/pxeger/ed887a9dc3566c98a8a11b77735f49b5
// ==/UserScript==

/* Go to Settings -> User Includes and add `https://chat.stackexchange.com/transcripts/*`
   if you want this to be enabled for historical chat transcripts as well
*/

(function() {
    'use strict';
    function hide() {
        for (const message of document.querySelectorAll(".system-message")) {
            if (message.innerText.match(/^\d+ hours? later…$/) || message.innerText.match(/^The last message was posted \d+ hours? ago.$/)) {
                message.parentElement.hidden = true;
            }
        }
    }
    const observer = new MutationObserver(hide);
    observer.observe(document.getElementById("chat"), {childList: true});
})();