Javascript粘滞便笺

(function() {
  const note = document.createElement('div');
  note.classList.add('note');
  note.textContent = 'This is a sticky note!';
  document.body.appendChild(note);

  window.addEventListener('scroll', function() {
    const note = document.querySelector('.note');
    if (window.scrollY > note.offsetTop) {
      note.style.position = 'fixed';
      note.style.top = '0';
      note.style.left = '0';
      note.style.right = '0';
      note.style.zIndex = '999999';
    } else {
      note.style.position = 'static';
      note.style.top = '';
      note.style.left = '';
      note.style.right = '';
      note.style.zIndex = '';
    }
  });
})();