To change the width of a table border, use the DOM border property. You can try to run the following code to change the width of a table border in JavaScript −
Example
<!DOCTYPE html>
<html>
<head>
<script>
function borderFunc(x) {
document.getElementById(x).style.border = "5px dashed blue";
}
</script>
</head>
<body>
<table style = "border:2px solid black" id = "newtable">
<tr>
<td>One</td>
<td>Two</td>
</tr>
<tr>
<td>Three</td>
<td>Four</td>
</tr>
<tr>
<td>Five</td>
<td>Six</td>
</tr>
</table>
<p>
<input type = "button" onclick = "borderFunc('newtable')"
value = "Change Border Width">
</p>
</body>
</html>