GitHub Earliest Commit UserScript.js

// ==UserScript==
// @name     GitHub "Earliest Commit"
// @version  1
// @grant    none
// @match    https://github.com/*
// ==/UserScript==

const exec = () => {
    const exists = (...sel) => {
        return sel.every((s) => document.querySelectorAll(s).length > 0);
    };

    if (!exists('.js-details-container strong', '.js-permalink-shortcut', '.js-permalink-shortcut', '#branch-select-menu')) {
        console.log('Exiting GitHub "Earliest Commit"');
        return;
    }

    const getEarliestCommitLogUrl = () => {
        const commits = parseInt(document.querySelector('.js-details-container strong').textContent.match(/[\d,]+/).pop().replace(/,/, ''))
        const hash = document.querySelector('.js-permalink-shortcut').href.match(/[a-f0-9]{40}$/).pop();
        const url = window.location.pathname.match(/^\/[\w-\.]+\/[\w-\.]+/).pop() + `/commits/master?after=${hash}+${commits - 36}`;

        return url;
    };
  

    const createButton = (event) => {
        const btn = document.createElement('div');
        btn.classList.add('btn', 'earliest-commit-log-btn');
        btn.textContent = 'Earliest Commit';
        btn.addEventListener('click', event);

        return btn;
    };

    const removeExistingButtons = () => {
        document.querySelectorAll('.earliest-commit-log-btn').forEach((e) => e.remove());
    };

    removeExistingButtons();

    const btn = createButton((event) => {
        window.location = getEarliestCommitLogUrl();
    });
  
  	el = document.querySelector('.file-navigation > .flex-auto');
  	if (!el) {
        el = document.querySelector('div.flex-self-center');
    }
  
    el.after(btn);
  
    console.log('exec');
};

exec();