Function to get to the first commit PAGE of any github repo.

first-commit-github.js

// copy and paste into devtools, press enter. voila
function githubFirstCommitsPage() {
  let el = document.querySelector('.repository-content');
  let base = el.querySelector('a[data-pjax]').href;
  let count = el.querySelector('.commits .num')
    .textContent
    .trim()
    .replace(/[^\d\.\-]/g, "");
  count = count-36;
  let sha = el.querySelector('.commit-tease-sha')
    .href
    .split('/');
  sha = sha[sha.length-1];
  window.location = `${base}?after=${sha}+${count}`;   
}

githubFirstCommitsPage();