onclick イベント

<ul>
  <li onclick="alert('HI');style.color='red';">いろは</li>
  <li>にほへ</li>
  <li>とちり</li>
</ul>

const second = document.querySelectorAll('li')[1];
const third = document.querySelectorAll('li')[2];
second.onclick = function() {
  this.style.color = 'blue';
};
third.addEventListener('click', (e) => e.target.style.fontSize = "2em");