Javascript导出页面表格数据到excel，如何让用户指定存储目录、输入报表名称？？

<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"> 
<title>EB页面导出为EXCEL文档的方法</title> 
<script type="text/javascript"> 
<!-- download
function saveCode(obj) { 
         var winname = window.open('', '_blank', 'top=10000'); 
         var strHTML = document.all.tableExcel.innerHTML; 
         winname.document.open('text/html', 'replace'); 
         winname.document.writeln(strHTML); 
         winname.document.execCommand('saveas','','excel.xls'); 
         winname.close(); 
} 
--> 
</script> 
</head> <body> 
<div id="tableExcel">  
<table id="test" width="100%" border="1" cellspacing="0" cellpadding="0"> 
     <tr> 
         <td colspan="5" align="center">WEB页面导出为EXCEL文档的方法</td> 
     </tr> 
     <tr> 
         <td>列标题1</td> 
         <td>列标题2</td> 
         <td>列标题3</td> 
         <td>列标题4</td> 
         <td>列标题5</td> 
     </tr> 
     <tr> 
         <td>aaa</td> 
         <td>bbb</td> 
         <td>ccc</td> 
         <td>ddd</td> 
         <td>eee</td> 
     </tr> 
     <tr> 
         <td>AAA</td> 
         <td>BBB</td> 
         <td>CCC</td> 
         <td>DDD</td> 
         <td>EEE</td> 
     </tr> 
     <tr> 
         <td>FFF</td> 
         <td>GGG</td> 
         <td>HHH</td> 
         <td>III</td> 
         <td>JJJ</td> 
     </tr> 
     <tr> 
       <td>aaa</td> 
       <td>bbb</td> 
       <td>ccc</td> 
       <td>ddd</td> 
       <td>eee</td> 
     </tr> 
     <tr> 
       <td>AAA</td> 
       <td>BBB</td> 
       <td>CCC</td> 
       <td>DDD</td> 
       <td>EEE</td> 
     </tr> 
     <tr> 
       <td colspan="5">FFFGGGHHHIIIJJJ</td> 
     </tr> 
     
     <tr> 
       <td>aaa</td> 
       <td>bbb</td> 
       <td>ccc</td> 
       <td>ddd</td> 
       <td>eee</td> 
     </tr> 
     <tr> 
       <td>AAA</td> 
       <td>BBB</td> 
       <td rowspan="4">CCCHHHcccccc</td> 
       <td>DDD</td> 
       <td>EEE</td> 
     </tr> 
     <tr> 
       <td>FFF</td> 
       <td>GGG</td> 
       <td>III</td> 
       <td>JJJ</td> 
     </tr> 
     
     <tr> 
       <td>aaa</td> 
       <td>bbb</td> 
       <td>ddd</td> 
       <td>eee</td> 
     </tr> 
     <tr> 
       <td>aaa</td> 
       <td>bbb</td> 
       <td>ddd</td> 
       <td>eee</td> 
     </tr> 
     <tr> 
       <td>AAA</td> 
       <td>BBB</td> 
       <td>CCC</td> 
       <td>DDD</td> 
       <td>EEE</td> 
     </tr> 
     <tr> 
       <td>FFF</td> 
       <td>GGG</td> 
       <td>HHH</td> 
       <td>III</td> 
       <td>JJJ</td> 
     </tr> 
</table> 
</div> 
<input type="button" value="另存为 Excel" onclick="saveCode(tableExcel)"> 
</body> 
</html>
http://hi.baidu.com/peterdai/blog/item/e7723b7beba963f50bd187ef.html
上面的代码我可以使用，但是当数据量很大的时候，就不行拉，如果你的数据比较少 ，应该可以用的~！请大家也帮帮忙，数据量大时，怎么做啊~！ 谢谢谢谢拉啊