Bookmarklet to get github repository creation time.

github-repo-created-at-bookmarklet.js

(function () {
  if (window.location.host !== 'github.com') {
    alert('Not a GitHub page.');
    return;
  }
  if (window.location.pathname.split('/').length < 3) {
    alert('Not in a repository page.');
    return;
  }
  function formatBytes(a, b) { if (0 == a) return "0 Bytes"; var c = 1024, d = b || 2, e = ["Bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"], f = Math.floor(Math.log(a) / Math.log(c)); return parseFloat((a / Math.pow(c, f)).toFixed(d)) + " " + e[f] }
  const cleanRepoName = window.location.pathname.split('/').splice(0, 3).join('/');
  fetch(`https://api.github.com/repos${cleanRepoName}`)
    .then(data => data.json())
    .then(json => {
      console.log('Github repo alert json',json);
      alert(`${cleanRepoName}\n\nCreated: ${new Date(json.created_at).toLocaleString('EN-GB')}\n\nSize: ${formatBytes(json.size*1024)}`)
    }).catch(e => alert(`${e.message}.\nSee console for more info.`));
})();