rolltogether.user.js

// ==UserScript==
// @name         RollTogether Helper
// @namespace    http://pabl.eu/
// @version      1.2
// @description  try to take over the world!
// @author       @pblop
// @match        https://www.crunchyroll.com/es/watch/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=crunchyroll.com
// @grant        none
// ==/UserScript==


function replace_urls(rollTogetherRoom) {
  const links = Array.from(document.querySelectorAll("a[href]")).filter(x => x.href.includes("watch") && !x.href.includes("rollTogetherRoom"));
  links.forEach(x => x.href = `${x.href}?rollTogetherRoom=${rollTogetherRoom}`);
}

(function() {
    'use strict';
    const urlParams = new URLSearchParams(window.location.search);
    const rollTogetherRoom = urlParams.get('rollTogetherRoom');

    console.log(rollTogetherRoom)

    window.addEventListener('load', ()=>replace_urls(rollTogetherRoom), false);
    setInterval(()=>replace_urls(rollTogetherRoom), 1000);
})();