请问怎么用JavaScript改变一表格中的数据呢?

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<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
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<script language="javascript">
function funcc11(){tbla.rows[0].cells[0].innerText="11"
tbla.rows[0].cells[1].innerText="22"
tbla.rows[2].cells[1].innerText="22"}
</script>
</HEAD><BODY>
<table id="tbla"  width="16%" border="1" style='table-layout:fixed;'>    <tr valign="top">
      <td  height="24" align="center">aa</td>
      <td height="24" align="center">bb</td>
    </tr>
    <tr valign="top">
      <td height="24" align="center">cc</td>
      <td height="24" align="center">vv</td>
    </tr>
    <tr valign="top">
      <td height="24" align="center">dd</td>
      <td height="24" align="center">ee</td>
    </tr></table>
<br><input type="button" id="tex2"  value="on_click change" onfocus="funcc11()"/>
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