<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function boom()
{
document.getElementById("q").appendChild(document.createElementNS("http://www.w3.org/1999/xhtml", "td"));
}
</script>
</head>
<body onload="boom();">
<table rules="cols"><thead><tr><th colspan="2"></th></tr></thead><tr></tr><tr id="q" style="border-left: 2px dotted yellow;"></tr></table>
</body>
</html>