Detect Rick Roll on Reddit.com

rickrolldetector.user.js

// ==UserScript==
// @name         Rick Roll Detector
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Detect Rick Roll on Reddit
// @author       /u/illuminist_ova
// @match        https://www.reddit.com/*
// @grant        none
// ==/UserScript==

(async function() {
  'use strict';

  const gistPage = 'https://api.github.com/gists/758717dfb7e68f4f9ed36aecee07c0e6'
  const selectorFile = 'rickrollselectors'
  const pageRes = await (await fetch(gistPage)).json()
  const fileInfo = pageRes.files[selectorFile]
  const selectors = fileInfo.content
    .split('\n')
    .filter(s=>s)
    .map(s=>s+'::after')
    .join(',')

  const head = document.head || document.getElementsByTagName('head')[0];
  const style = document.createElement('style');
  style.type = 'text/css';
  style.id = "detect_rickroll";
  style.appendChild(document.createTextNode(selectors + "{content:'ITS RICK ROLL!!!';font-size:0.6em;vertical-align:super;}"));
  head.appendChild(style);
})();

rickrollselectors

a[href*='dQw4w9WgXcQ']
a[href*='ub82Xb1C8os']
a[href*='oHg5SJYRHA0']
a[href*='0JgF4CMXU9M']