<html>
<body>
<script language="JavaScript">
function function1() {
var newAttr = document.createAttribute("width");
newAttr.nodeValue = "400px"
document.getElementById("myB").setAttributeNode(newAttr);
}
</script>
<table id="myB" border=3 cellpadding="5" style="border-color:blue">
<tr>
<th>Expand this table</th>
<th>This is another cell</th>
<th>This is another cell</th>
<th>This is another cell</th>
<th>This is another cell</th>
<th>This is another cell</th>
<th>This is another cell</th>
<th>This is another cell</th>
<th>This is another cell</th>
<tr>
</table>
<input id="myB" type="button" value="Add attribute to the table" onclick="function1();">
</body>
</html>