请问如何才使一段JS代码加载一个特定的文件

把这个插进 123.html 就OK
<iframe src="999.asp" frameborder=0 width="" height=""></ifrmae>

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>Test</title>
<script>
function window.onload(){
  //window.setInterval("fresh()",1000);
  fresh();
}
function fresh(){
alert("fresh()");
  var dt = new Date();
  var url = "999.asp";
  var xml = new ActiveXObject("Microsoft.XMLHTTP");
  xml.open("GET",url,false);
  //xml.open("POST",url);
  xml.setRequestHeader("context-type","text/html;charset=gb2312");
  xml.send();   if(xml.readystate!=4){
     alert("a");
     return;
  }
   var objXML = xml.responseText;
    mydiv.innerHTML = objXML;
    //objwin = window.open("","");
    //objwin.document.write ( objXML );
    //objwin.document.close;
    //alert( objXML );
   //test2(objXML);
}
function test2(obj){
var xmlDoc = new ActiveXObject("Msxml2.DOMDocument.4.0");
var root;
var MyText;
var MyNewNode;
xmlDoc.async = false;
xmlDoc.resolveExternals = false;
xmlDoc.loadXML(obj);
if (xmlDoc.parseError.errorCode != 0) {
var myErr;
myErr = xmlDoc.parseError;
alert("You have error " + myErr.reason);
}
else {
alert(xmlDoc.xml);
//mydiv.innerHTML = xmlDoc.xml;
}
}
</script>
</head> <body>
<DIV ID="mydiv"></DIV> </body>
</html>
还可以在js中用document.write写，write的内容还是需要用xmlHttp来获取，参见 fantiny的方法
，但是不必要等到onload在做也可以，
记住，如果用document.write的话，必须是在onload调用之前调用document.write。