javascript与xmlhttp联合实现文件下载

<script language="javascript">
var xh;
function getXML(geturl)
{
xh = new ActiveXObject("Microsoft.XMLHTTP");
xh.onreadystatechange = getReady;
xh.open("GET",geturl,true);                    
xh.send();  
                         
}

function getReady()
{
alert(xh.readyState);
if(xh.readyState==4)
{
if(xh.status==200)
{saveFile("d:/rss.xml");return true;}
else
{return false;}
}
else
return false;
}

function saveFile(tofile)
{
var objStream;
var imgs;
imgs = xh.responseBody; 
objStream = new ActiveXObject("ADODB.Stream");
objStream.Type = 1;
objStream.open();
objStream.write(imgs);
objStream.SaveToFile(tofile)
}
getXML('http://yoyokee.com/demo/rss.xml');
</script>