tampermonkey-hackernews-favicons.js

// ==UserScript==
// @name         HN Favicons
// @version      0.3
// @license MIT
// @description  Favicons for Hacker News
// @match        https://*.ycombinator.com/*
// @grant        GM.addElement
// ==/UserScript==

for(let link of document.links) {
  if(!link.href.match("ycombinator.com") && !link.href.match("javascript:void") && link.firstChild.nodeName !== "IMG") {
    const domain = new URL(link.href).hostname
    const imageUrl = `https://icons.duckduckgo.com/ip3/${domain}.ico`
    const container = document.createElement('span');
    container.style.paddingRight = '0.25em';
    container.style.paddingLeft = '0.25em';
    link.prepend(container);
    GM.addElement(container, 'img', {
      src: imageUrl,
      width: 12,
      height: 12
    });
  }
}