Stack Overflow: marcar las respuestas antiguas

/* Flag answers older than a chosen year as possibly outdated */
(function () {
  var CUTOFF = 2018;
  function mark() {
    document.querySelectorAll('#answers .answer').forEach(function (a) {
      if (a.dataset.sofAge) return;
      var t = a.querySelector('.user-action-time time, .relativetime');
      var iso = t && (t.getAttribute('datetime') || t.getAttribute('title'));
      if (!iso) return;
      var year = new Date(iso).getFullYear();
      if (!isNaN(year) && year < CUTOFF) {
        a.dataset.sofAge = '1';
        var tag = document.createElement('div');
        tag.textContent = '⚠ Possibly outdated (' + year + ')';
        tag.style.cssText = 'background:#fff4d6;color:#7a5b00;padding:4px 8px;border-radius:4px;margin:6px 0;font-size:12px;font-weight:600;';
        var cell = a.querySelector('.answercell') || a;
        cell.insertBefore(tag, cell.firstChild);
      }
    });
  }
  mark();
  new MutationObserver(mark).observe(document.body, { childList: true, subtree: true });
})();