<input type="button" onclick="alertTd2()" value="Alert cell index of 'Griffin'" />
<html>
<head>
<script type="text/javascript">
function alertTd1()
{
alert(document.getElementById('td1').cellIndex);
}
function alertTd2()
alert(document.getElementById('td2').cellIndex);
</script>
</head>
<body>
<table border="1">
<tr>
<th>Firstname</th>
<th>Lastname</th>
</tr>
<td id="td1">Peter</td>
<td id="td2">Griffin</td>