Minha tabela está no formato

<table id="mytable">
<thead>
  <tr>
    <th>name</th>
    <th>place</th>
  </tr>
</thead>
<tbody>
<tr>
   <td>adfas</td>
   <td>asdfasf</td>
</tr>
</tbody>
</table>

Encontrei o seguinte código online. Mas não funciona se eu usar as tags "thead" e "tbody"

function write_to_excel() {

    str = "";

    var mytable = document.getElementsByTagName("table")[0];
    var rowCount = mytable.rows.length;
    var colCount = mytable.getElementsByTagName("tr")[0].getElementsByTagName("td").length;

    var ExcelApp = new ActiveXObject("Excel.Application");
    var ExcelSheet = new ActiveXObject("Excel.Sheet");
    ExcelSheet.Application.Visible = true;

    for (var i = 0; i < rowCount; i++) {
        for (var j = 0; j < colCount; j++) {
            str = mytable.getElementsByTagName("tr")[i].getElementsByTagName("td")[j].innerHTML;
            ExcelSheet.ActiveSheet.Cells(i + 1, j + 1).Value = str;
        }
    }