<!DOCTYPE html>
<html>
<head>
<style>
table, th, td {
border: 1px solid black;
}
</style>
</head>
<body>
<p>Click the "Try it" button to change the border-collapse property of the TABLE element:</p>
<button onclick="myFunction()">Try it</button>
<table id="myTABLE">
<tr>
<th>Name</th>
<th>Age</th>
</tr>
<tr>
<td>Emil</td>
<td>9</td>
</tr>
<tr>
<td>Tobias</td>
<td>7</td>
</tr>
<tr>
<td>Linus</td>
<td>2</td>
</tr>
</table>
<script>
function myFunction() {
document.getElementById("myTABLE").style.borderCollapse = "collapse";
}
</script>
</body>
</html>