JavaScript 生成表格的语句里怎样设置行隐藏

L@_@K
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title> new document </title>
    <meta name="generator" content="editplus" />
    <meta name="author" content="Gao YiXiang" />
    <meta name="email" content="[email protected]" />
    <meta name="keywords" content="javascript dhtml dom" />
    <meta name="description" content="I love web development." />
</head>
<body>
    <table border="1">
        <tr id="trFirst">
            <td>r11</td>
            <td>r12</td>
        </tr>
        <tr>
            <td>r21</td>
            <td>r22</td>
        </tr>
        <tr>
            <td>r31</td>
            <td>r32</td>
        </tr>
    </table>
    <input type="button" id="btnHideFirst" value="Hidden first row" />
    <script type="text/javascript">
    <!--
var oBtn = document.getElementById("btnHideFirst");
oBtn.onclick = function()
{
    var oTr = document.getElementById("trFirst");
    if (oTr)
    {
        oTr.style.setAttribute("display", "none");
    }
};
    //-->
    </script>
</body>
</html>