<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>
<script type="text/javascript">
var data = [];
$(function(){
    $('tr').each(function(){
        var x = $(this).find("td:first").html();
        var y = $(this).find("th").html();
        data.push({
            x:x,
            y:y
        });
        alert(x + " " + y)
    })
    alert(data.length)
})
</script>
<table>
<tbody>
  <tr>
  <td>1</td>
  <th>300</th>
  </tr>
  <tr>
  <td>2</td>
  <th>400</th>
  </tr>
</tbody>
</table>