GitHub: PR author avatar as tab icon

Sets GitHub PR tab icon (favicon) to author's avatar

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         GitHub: PR author avatar as tab icon
// @namespace    https://github.com/rybak
// @version      6
// @description  Sets GitHub PR tab icon (favicon) to author's avatar
// @author       Andrei Rybak
// @homepageURL  https://github.com/rybak/github-pr-avatars-tab-icons
// @license      MIT
// @match        https://github.com/*/pull/*
// @icon         https://github.githubassets.com/favicons/favicon-dark.png
// @grant        none
// ==/UserScript==

/*
 * Copyright (c) 2023 Andrei Rybak
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/*
 * Doesn't work very good, because GitHub's tab icons aren't static.
 * Results of GitHub Actions builds are reflected in the icons dynamically.
 */

(function() {
	'use strict';

	const LOG_PREFIX = '[PR avatars]';

	function error(...toLog) {
		console.error(LOG_PREFIX, ...toLog);
	}

	function log(...toLog) {
		console.log(LOG_PREFIX, ...toLog);
	}

	/*
	 * Extracts the parts 'owner_repo' and 'pull_number' out of the current page's URL.
	 */
	function getPullRequestUrlParts() {
		/*
		 * URL might be just a PR link:
		 *   https://github.com/rybak/atlassian-tweaks/pull/10
		 * or a subpage of a PR:
		 *   https://github.com/rybak/atlassian-tweaks/pull/10/commits
		 * Result will be
		 *   'rybak/atlassian-tweaks' and '10'
		 */
		const m = document.location.pathname.match("^/(.*)/pull/(\\d+)");
		if (!m) {
			error("Cannot extract owner_repo and pull_number for REST API URL from", document.location.pathname);
			return null;
		}
		return {
			'owner_repo': m[1],
			'pull_number': m[2]
		};
	}

	/*
	 * Generates a URL for accessing the data about the pull request via GitHub's REST API.
	 * https://docs.github.com/en/rest/pulls/pulls?apiVersion=2022-11-28#get-a-pull-request
	 */
	function getRestApiPullRequestUrl() {
		const parts = getPullRequestUrlParts();
		if (!parts) {
			return null;
		}
		return `https://api.github.com/repos/${parts.owner_repo}/pulls/${parts.pull_number}`;
	}

	/*
	 * Replaces favicon with the PR author's avatar.
	 */
	async function setFavicon() {
		const prUrl = getRestApiPullRequestUrl();
		if (!prUrl) {
			return;
		}
		try {
			const response = await fetch(prUrl);
			const json = await response.json();
			const avatarUrl = json.user.avatar_url;
			if (!avatarUrl) {
				error("Cannot find the avatar URL", json);
				return;
			}
			const faviconNodes = document.querySelectorAll('link[rel="icon"], link[rel="alternate icon"]');
			if (!faviconNodes || faviconNodes.length == 0) {
				error("Cannot find favicon elements.");
				return;
			}
			log("New URL", avatarUrl);
			faviconNodes.forEach(node => {
				log("Replacing old URL =", node.href);
				node.href = avatarUrl;
			});
		} catch (e) {
			error(`Cannot load ${prUrl}. Got error`, e);
		}
	}

	setFavicon();
})();