<html>
<head>
<script type="text/javascript">
function alertRowIndex()
{
alert(document.getElementById("tr4").parentNode.innerHTML);
alert(document.getElementById("tr4").rowIndex);
}
function addRow()
{
var tr3=document.getElementById("tr3");
var tr4=tr3.cloneNode(true);
tr4.id="tr4";
tr3.parentNode.appendChild(tr4);
}
</script>
</head>
<body>
<table border="1">
<tr id="tr1">
<th>Firstname</th>
<th>Lastname</th>
</tr>
<tr id="tr2">
<td>Peter</td>
<td>Griffin</td>
</tr>
<tr id="tr3">
<td>Peter</td>
<td>Griffin</td>
</tr>
</table>
<br />
<input type="button" onclick="alertRowIndex()" value="Alert row
index" />
<input type="button" onclick="addRow()" value="Add new row" />
</body>
</html>