Implementation code display of JS control table alternating row color

<table width="800" border="0" cellpadding="0" cellspacing="0">
    <tr>
        <td>不变色</td>
    </tr>
    <tbody id="goaler">
    <tr>
        <td>xxxxxxxx</td>
    </tr>
    <tr>
        <td>xxxxxxxx</td>
    </tr>
    <tr>
        <td>xxxxxxxx</td>
    </tr>
    <tr>
        <td>xxxxxxxx</td>
    </tr>
    </tbody>
    <tr>
        <td>不变色</td>
    </tr>
</table>
<script language="JavaScript">
<!--
var TbRow = document.getElementById("goaler");
if (TbRow != null)
{
    for (var i=0;i<TbRow.rows.length ;i++ )
    {
        if (TbRow.rows[i].rowIndex%2==1)
        {
            TbRow.rows[i].style.backgroundColor="";
        }
        else
        {
            TbRow.rows[i].style.backgroundColor="#F1F1F1";
        }
    }
}
//-->
</script>