varför blir det undefined när man klickar på den första boxen?
<html>
<head>
<script type="text/javascript">
function checkAllCheckboxes(o, frmName, fldName)
{
alert(document.getElementById('list').elements['mark'].length);
}
</script>
</head>
<body>
<form id="list" method="post">
<table id="table" width="100%" cellspacing="1" cellpadding="2" border="0">
<tr>
<th style="height:20px; width:20px;"><input name="markAll" id="markAll" type="checkbox" value="all" title="Markera eller avmarkera alla." onClick="checkAllCheckboxes(this, 'list', 'mark');"><label for="markAll" class=""></label></th></tr>
<tr id="tr2">
<td class="" style=""><input name="mark" id="2" type="checkbox" value="2" title="Markera eller avmarkera denna." onClick="markTDParent(this);"></td>
</tr>
</table>
</form>
</body>
</html>