Tampermonkey - Add link to Jira on Github PR

link_to_jira_pr.user.js

// ==UserScript==
// @name         Add link to Jira on Github PR
// @version      0.3.0
// @author       Nathan Marcos
// @match        https://github.com/trivago/*/pull/*
// @run-at       document-end
// ==/UserScript==

(function () {
    'use strict';

    const setLink = titleElement => {
        const title = titleElement.innerText;
        const taskIdMatch = title.match(/([a-z\|A-Z]+[-\|\s][0-9]+)/g)[0];
        const taskId = taskIdMatch.replace(' ', '-').concat(' ');
        const newTitle = title.replace(taskIdMatch, '').trim();
        titleElement.innerText = '';

        const linkElement = document.createElement("a");
        linkElement.href = `https://trivago.atlassian.net/browse/${taskId}`;
        linkElement.text = taskId;
        linkElement.target = '_blank';
        titleElement.classList.add("jira-link");
        titleElement.append(linkElement);

        const spanElement = document.createElement("span");
        spanElement.innerText = newTitle;
        titleElement.append(spanElement);
    };

    var observer = new MutationObserver(function (mutations, me) {
        const titleElement = document.getElementsByClassName('js-issue-title')[0];
        if (titleElement && !titleElement.classList.contains('jira-link')) {
            setLink(titleElement);
            return;
        }
    });

    observer.observe(document, {
        childList: true,
        subtree: true
    });

})();