Github user script: Show a open PR link when an issue has label "3 - code review"

open_pr_link.user.js

// ==UserScript==
// @name        Open PR Link
// @namespace   ghprlink
// @description Show a open PR link when an issue has label "3 - code review"
// @include     https://github.com/*
// @version     1
// @grant       none
// ==/UserScript==

function addOpenPRLinks(){
    if(/open_first_pr=1/.test(location.search)) {
        let pr = document.querySelector('div[id^=ref-pullrequest] ~ h4 a');
        if(pr){
            location.href = pr.href;
        } else {
            alert('PR not found');
        }
    }

    let labels = document.querySelectorAll('.labels a[title="Label: 3 - code review"]');
    Array.from(labels).forEach(label => {
        let issueLink = label.parentNode.previousElementSibling;
        if(issueLink && issueLink.tagName == 'A') {
            let prLink = document.createElement('a');
            prLink.setAttribute('href', issueLink.getAttribute('href') + '?open_first_pr=1');
            prLink.className = issueLink.className.replace(/\bh4\b/, 'h5');
            prLink.appendChild(document.createTextNode('[open pr]'));
            issueLink.parentNode.insertBefore(prLink, label.parentNode)
        }
    });
}
addOpenPRLinks()
document.addEventListener('pjax:end', addOpenPRLinks);