SOURCE

    let list = document.getElementsByTagName('li');
    for (let i = 0; i < list.length; i++) {
      list[i].addEventListener('click', function () {
        alert(i + 1)
      }, true)
    }

  <ul>
    <li>编号1，点击我请弹出1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
  </ul>