teddit-redirect.js

// ==UserScript==
// @name        Redirect to teddit
// @description Automatically redirect from Reddit to Teddit
// @match       https://old.reddit.com/*
// @match       https://www.reddit.com/*
// @match       https://reddit.com/*
// @grant       none
// @run-at      document-start
// ==/UserScript==

(function () {
    'use strict';
    const instance = 'teddit.net'
    location.hostname = `${instance}`;
})();