javascript实现保存文本与修改文本，只做出来了保存文本，想问修改该怎么做，求指教。

用户名：

姓名	性别	年龄	籍贯	操作
张三	女	10	万州

 function saveOrder() {
var w = window.open("", "导出", "height=0,width=0,toolbar=no,menubar=no,scrollbars=no,resizable=on,location=no,status=no");

var dt = new Date();
w.document.charset = "UTF-8";
w.document.write("订单号："+document.getElementByIdx_x('oidspan').innerHTML+'，生成日期：'+dt.getFullYear()+"-"+(dt.getMonth()+1)+"-"+dt.getDate());
w.document.execCommand("SaveAs", false, "订单号.txt");
w.close();
}
我用这个代码查看dynamics crm页面的源码来用的
function saveOrder() {
var w = window.open("", "导出", "height=0,width=0,toolbar=no,menubar=no,scrollbars=no,resizable=on,location=no,status=no");

var dt = new Date();
w.document.charset = "UTF-8";
w.document.write(window.body.innerHTML);
}

 <a onclick='alert(search)'>search</a> 
<script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.9.1.min.js"></script>
<table>
    <tr>
        <td>用户名：</td>
        <td><input onblur="fun(this)" /></td>
        <td><img src="yes.gif" style="display:none" /><img src="no.png" style="display:none" /></td>
    </tr>
</table>
<table width="700px" cellspacing="0" border="1px" bordercolor="#00FFFF" id="td">
    <tr>
        <td>姓名</td>
        <td>性别</td>
        <td>年龄</td>
        <td>籍贯</td>
        <td>操作</td>
    </tr>
    <tr>
        <td>张三</td>
        <td>女</td>
        <td>10</td>
        <td>万州</td>
        <td><input type="button" value="修改" onclick="fun2(this)" /></td>
    </tr>
</table>
</div>
<input type="button" value="添加一行" onclick="fun1()" />
<script type="text/javascript">
    function modify(btn) {
    }
    function fun(ip) {
        var td = ip.parentNode;
        var tr = td.parentNode;
        var tds = tr.cells;
        tds.item(2).childNodes.item(0).style.display = "block";
        tds.item(2).childNodes.item(1).style.display = "block";
    }
    function fun1() {
        var tb = document.getElementById("td");
        var nameinput = document.createElement("input");
        var seseinput = document.createElement("input");
        var ageinput = document.createElement("input");
        var jginput = document.createElement("input");
        var btinput = document.createElement("input");
        btinput.type = "button";
        btinput.value = "保存";
        btinput.setAttribute("onclick", "fun2(this)");
        var nametd = document.createElement("td");
        var sestd = document.createElement("td");
        var agetd = document.createElement("td");
        var jptd = document.createElement("td");
        var bTtd = document.createElement("td");

        nametd.appendChild(nameinput);
        sestd.appendChild(seseinput);
        agetd.appendChild(ageinput);
        jptd.appendChild(jginput);
        bTtd.appendChild(btinput);

        var tr = document.createElement("tr");
        tr.appendChild(nametd)
        tr.appendChild(sestd)
        tr.appendChild(agetd)
        tr.appendChild(jptd)
        tr.appendChild(bTtd)
        td.appendChild(tr);
    }
    function fun2(bt) {
        var tds = bt.parentNode.parentNode.cells;
        if (bt.value == "保存") {

            var a = tds.item(0).childNodes.item(0).value;
            var b = tds.item(1).childNodes.item(0).value;
            var c = tds.item(2).childNodes.item(0).value;
            var d = tds.item(3).childNodes.item(0).value;

            tds.item(0).innerHTML = a;
            tds.item(1).innerHTML = b;
            tds.item(2).innerHTML = c;
            tds.item(3).innerHTML = d;
            bt.value = "修改";
        }
        else {
            tds[0].innerHTML = '<input type="text" value="' + tds[0].innerHTML.replace(/"/g, '&quot;') + '"/>'
            tds[1].innerHTML = '<input type="text" value="' + tds[1].innerHTML.replace(/"/g, '&quot;') + '"/>'
            tds[2].innerHTML = '<input type="text" value="' + tds[2].innerHTML.replace(/"/g, '&quot;') + '"/>'
            tds[3].innerHTML = '<input type="text" value="' + tds[3].innerHTML.replace(/"/g, '&quot;') + '"/>'
            bt.value = "保存";

        }
    }
</script>