<!DOCTYPE html>
<html>
<head>
<style>
table, td {
    border: 1px solid black;
}

</style>
</head>
<body>

<p>Click the buttons to create and delete a tfoot element for the table.</p>

<table id="myTable">
  <tr>
    <td>cell 1</td>
    <td>cell 2</td>
  </tr>
  <tr>
    <td>cell 3</td>
    <td>cell 4</td>
  </tr>
</table>
<br>

<button onclick="myCreateFunction()">Create tfoot</button>
<button onclick="myDeleteFunction()">Delete tfoot</button>

<script>
function myCreateFunction() {
    var table = document.getElementById("myTable");
    var footer = table.createTFoot();
    var row = footer.insertRow(0);
    var cell = row.insertCell(0);
    cell.innerHTML = "<b>This is a table footer</b>";
}

function myDeleteFunction() {
    document.getElementById("myTable").deleteTFoot();
}
</script>

</body>
</html>