[trikadin]

<table id="table">
<tr>
<td>1</td><td>2</td>
</tr>
<tr>
<td>3</td><td>4</td>
</tr>
</table>

<script>
var td = document.getElementById("table").getElementsByTagName("td");
for (var i=0; i<td.length; ++i) 
  alert(td[i].innerHTML);
</script>