A ViolentMonkey/TamperMonkey/GreaseMonkey script for setting unread notification badges for Github.com

github-notification-badges.js

// ==UserScript==
// @name GitHub Notification Badges
// @namespace Violentmonkey Scripts
// @match https://github.com/*
// @grant none
// ==/UserScript==
// 

const getNotificationsCount = async () => {
  const response = await fetch('https://github.com/notifications');
  const text = await response.text();
  
  const doc = document.createElement('html');
  doc.innerHTML = text;
  
  const notifications = doc.querySelectorAll('.js-notification.unread');
  return notifications.length;
}

const hasUnread = () => {
  return !!document.querySelector('.mail-status.unread');
}

const updateBadge = async () => {
  const Badge = navigator.setAppBadge || navigator.setExperimentalAppBadge;
  if (!Badge)
    return;
  
  const notificationCount = await getNotificationsCount();
  Badge.call(navigator, notificationCount);
}

const poll = async (promise, regularity) => {
  await promise();
  setTimeout(() => {
    poll(promise, regularity);
  }, regularity)
};

poll(updateBadge, 5000);
getNotificationsCount();