鼠标悬停在一个标签上时，显示一段文字的两种方法

1.使用title：如果使用title属性时很方便，但是不灵活

<table border="1">
 <tr>
  <td title="鼠标停留显示内容1">文字内容1</td>
 </tr>
</table>

2.可以监听鼠标事件onmouseover

<table border="1">
 <tr>
  <td onmouseover="overShow()" onmouseout="outHide()">文字内容2</td>
 </tr>
</table>
<div id="showDiv" style="position: absolute; background-color: white; border: 1px solid black;"></div>
<script>
 function overShow() {
  var showDiv = document.getElementById('showDiv');
  showDiv.style.left = event.clientX;
  showDiv.style.top = event.clientY;
  showDiv.style.display = 'block';
  showDiv.innerHTML = '鼠标停留显示内容2';
 }
 
 function outHide() {
  var showDiv = document.getElementById('showDiv');
  showDiv.style.display = 'none';
  showDiv.innerHTML = '';
 }
</script>