在JS中给动态生成的控件属性赋值

<script language="javascript" type="text/javascript">
    function f1(name,Num) 
    { 
        var len = 0; 
        var str=document.getElementById(name).value;
        for (var i=0; i<str.length; i++)
        { 
            if (str.charCodeAt(i)>127 || str.charCodeAt(i)==94) 
            { 
            len += 2; 
            } 
            else 
            { 
                len ++; 
            } 
        } 
        
        if(len > Num)
        {
            1 //在此位置addRow方法中添加的text的控件的属性maxlength的值设置为8，请问该怎么实现
        }
    } 
    
    function addRow()
    {
        var tblDetail = document.getElementById("tblDetail");
        var bodyRow = tblDetail.insertRow();
        
        var name ="aaa"
        var td = bodyRow.insertCell();
            td.innerHTML = "<input id='"+name+"' type='text' style='width:100%;' onchange=f1('"+name+"',8) />";
     }
</script><body>
    <form id="form1" runat="server">
        <table>
             <tr>
                <td>
                    <table id="tblDetail" bgcolor="#ffffff" border="1" bordercolor="#cccccc" cellpadding="1"
                        cellspacing="0" class="tableBorder" style="border-collapse: collapse" width="100%">
                        <tr>
                            <td style="font-weight: bold;">
                                名称
                            </td>
                         </tr>
                    </table>
                </td>
                <td>
                 <a id="aAddRow" style="width: 48px;" href="javascript:addRow()">添加一行</a>
                </td>
            </tr>
        </table>
    </form>
</body>
</html>
想要实现js中f1方法的注释部分的功能，请问该怎么写代码