Quora: skoki między odpowiedziami klawiszami J/K

// Jump between answers with the J and K keys
document.addEventListener('keydown', function (e) {
  if (e.ctrlKey || e.metaKey || e.altKey) { return; }
  const tag = (e.target.tagName || '').toLowerCase();
  if (tag === 'input' || tag === 'textarea' || e.target.isContentEditable) { return; }
  if (e.key !== 'j' && e.key !== 'k') { return; }
  const answers = Array.prototype.slice.call(
    document.querySelectorAll('div[class*="puppeteer_test_answer_content"]')
  );
  if (!answers.length) { return; }
  const y = window.scrollY + 80;
  let idx = answers.findIndex(function (a) {
    return a.getBoundingClientRect().top + window.scrollY > y;
  });
  if (e.key === 'k') { idx = idx - 2; }
  idx = Math.max(0, Math.min(answers.length - 1, idx < 0 ? answers.length - 1 : idx));
  answers[idx].scrollIntoView({ behavior: 'smooth', block: 'start' });
});