​x
 
<!DOCTYPE html>
<html>
<head>
<style>
table, th, td {
  border: 1px solid black;
}
</style>
</head>
<body>
​
<p>单击按钮返回 thead 元素的 innerHTML。</p>
​
<table id="myTable">
   <thead>
     <tr>
       <th>月份</th>
       <th>存款</th>
     </tr>
   </thead>
   <tfoot>
     <tr>
       <td>合计</td>
       <td>$180</td>
     </tr>
   </tfoot>
   <tbody>
     <tr>
       <td>一月</td>
       <td>$100</td>
     </tr>
     <tr>
       <td>二月</td>
       <td>$80</td>
     </tr>
   </tbody>
</table>
<br>
​
<button onclick="myFunction()">试一试</button>
​
<script>
function myFunction() {
  alert(document.getElementById("myTable").tHead.innerHTML);
}
</script>
​
</body>
</html>
​