用戶校驗

var req;
 var which;
 var url;
 function retrieveURL(url2) {

url = url2+"?name="+document.getElementById("uname").value;
 if (window.XMLHttpRequest) { // Non-IE browsers
 req = new XMLHttpRequest();
 req.onreadystatechange = processStateChange;
 try {
 req.open("GET", url, true);
 } catch (e) {
 alert('創建對象失敗');
 }
 req.send(null);
 } else if (window.ActiveXObject) { // IE
 req = new ActiveXObject("Microsoft.XMLHTTP");
 if (req) {
 req.onreadystatechange = processStateChange;
 req.open("GET", url, true);
 req.send(null);
 }
 }
 }
 function processStateChange(){
   if (req.readyState == 4) { // Complete
      if (req.status == 200) { // OK response
        document.getElementById("name").innerHTML = req.responseText;
   } else {
      alert("Problem: " + req.statustext);
 }
 }
 }