[Tampermonkey] GitHub reveal all comments button

revealAllComments.js

// ==UserScript==
// @name         GitHub reveal all comments button
// @namespace    http://tampermonkey.net/
// @version      1.0.0
// @description  Useful on the PR page after review
// @author       feimosi
// @match        https://github.com/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    function addRevealCommentsButton() {
        const header = document.querySelector('.gh-header-actions');
        const revealButton = document.querySelector('.show-reveal-comments-button');
        if (!header || revealButton) {
            return;
        }

        const button = document.createElement('button');
        button.type = 'button';
        button.className = 'btn btn-sm show-reveal-comments-button';
        button.innerText = 'Reveal comments';
        button.onclick = function(e) {
            e.preventDefault();
            document.querySelectorAll('.show-outdated-button').forEach(b => b.click());
        };

        header.appendChild(button);
    }

    setInterval(addRevealCommentsButton, 2000);
})();

You're welcome! :)