​x
 
<!DOCTYPE html>
<html>
<head>
<style>
td, th {
  border: 1px solid black;
}
</style>
</head>
<body>
​
<table id="myTable" style="border-collapse:collapse;">
  <tr>
    <th>月份</th>
    <th>存款</th>
  </tr>
  <tr>
    <td>一月</td>
    <td>$100</td>
  </tr>
  <tr>
    <td>二月</td>
    <td>$150</td>
  </tr>
</table>
<br>
​
<button type="button" onclick="myFunction()">返回边框折叠</button>
​
<script>
function myFunction() {
  alert(document.getElementById("myTable").style.borderCollapse);
}
</script>
​
</body>
</html>
​