Ajax Detection User Name

<div id= "B" >test</div>
<script>
function Createajax () {//It will return XMLHTTP object instance
var _xmlhttp;
try {
_xmlhttp=new ActiveXObject ("Microsoft.XMLHTTP"); How IE is created
}
catch (e) {
try {
_xmlhttp=new XMLHttpRequest (); How to create a browser such as FF
}
catch (e) {
_xmlhttp=false; Returns False if the creation fails
}
}
return _xmlhttp; Returns the XMLHTTP object instance

}
var exitdos =createajax ();
Alert (Exitdos)
Exitdos.open ("Get", "www.111cn.net", true);
exitdos.onreadystatechange= function ()
{
if (exitdos.readystate = = 1) {document.getElementById ("B"). Innerhtml= "Check ..."}
if (exitdos.readystate==4)
{

(= &&)
Alert (Exitdos.status)
alert (Exitdos.responsetext);
}
}
Exitdos.send (NULL);
</script>