topic_save.js

// ==UserScript==
// @name         Topic Saver
// @updateURL    https://gist.github.com/12944qwerty/2e8b2741b19e8eeff1628028a782e88a/raw/2335b2fe9d1275766703fc5827327921fa754899/topic_save.js
// @version      0.1
// @description  An autosaver for topics on WoX.
// @author       12944qwerty
// @match        https://worldofolympians.com/topic/view/*
// @match        https://worldoflegend.eu/topic/view/*
// @match        https://worldofpotter.com/topic/view/*
// @match        https://worldofpotter.eu/topic/view/*
// @match        https://worldofgladersunited.com/topic/view/*
// @match        https://worldofmetahumans.com/topic/view/*
// @match        https://worldofnephilim.com/topic/view/*
// @match        https://worldofpotter.de/topic/view/*
// @match        https://worldofwalkers.com/topic/view/*
// @match        https://worldofthrones.com/topic/view/*
// @match        https://worldofbendingarts.com/topic/view/*
// @match        https://worldofunseenarts.com/topic/view/*
// @match        https://worldofjademountain.com/topic/view/*
// @match        https://worldofforgottendungeons.com/topic/view/*
// @match        https://worldoffairytales.com/topic/view/*
// @match        https://worldofsupernaturals.com/topic/view/*
// @match        https://worldofalagaesia.com/topic/view/*
// @match        https://worldofmysticfalls.com/topic/view/*
// @match        https://worldofgalaxies.com/topic/view/*
// @match        https://worldofmetahumans.com/topic/view/*
// @match        https://worldofhungergames.es/topic/view/*
// @match        https://worldofteenwolf.nl/topic/view/*
// ==/UserScript==

const elemId = 'topic-input';
var user = document.querySelectorAll(".username-popup,.profile-link")[1].text;
document.getElementById(elemId).addEventListener('change', e => {
  window.localStorage[elemId + window.location.href+user] = e.target.value;
});
window.addEventListener('load', () => {
  document.getElementById(elemId).value = window.localStorage[elemId + window.location.href+user];
});