我试着在点击元素HomeNav下的导航栏中的第二个li时显示警报。您可以在codepen上签出完整的代码

var linkButton = document.getElementById('#homenav li:nth-child(2) a');
if(linkButton) {
  linkButton.addEventListener('click', function() {
    alert('Test');
  });
}

HTML

<div id="homenav">
<div class="navbar navbar-default  navbar-fixed-top" role="navigation">
  <div class="container">
    <div class="navbar-header">
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
    </div>
    <div id="navbar" class="navbar-collapse collapse">
      <ul class="nav navbar-nav"></ul>
      <ul class="nav navbar-nav navbar-right">
        <li>
          <a href="#">Home</a>
        </li>
        <li>
          <a href="#">Table Ranking</a>
        </li>
        <li>
          <a href="#">Blog</a>
        </li>
            </ul>
    </div>
  </div>
</div>
</div>