S.E.K.T.O.R.,
<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style>
table, td { border: 1px solid black; }
</style>
</head>
<body>
<table>
<tbody id="mytestid">
<tr>
<td>lalala</td>
</tr>
<tr>
<td>lalala</td>
</tr> </tbody>
</table>
<button>Add cells</button>
<script>
var button = document.getElementsByTagName('button')[0],
tbody = document.getElementById('mytestid'),
data = '<tr><td>.1.1.</td></tr><tr><td>.2.2.</td></tr>';
button.onclick = function() {
var temp, div;
while(temp = tbody.firstChild) {
tbody.removeChild(temp);
}
div = document.createElement('div');
div.innerHTML = '<table><tbody>' + data + '</tbody></table>' ;
div = div.getElementsByTagName('tbody')[0];
while(temp = div.firstChild) {
tbody.appendChild(temp);
}
};
</script>
</body>
</html>