ajax验证用户名和密码

 1     var user = form.name.value;
 2     var password = form.password.value;
 3     var url = "chkname.php?user="+user+"&password="+password;//以前只知道ajax用于对用户名的检测，原来还可以对密码进行检测。
 4     xmlhttp.open("GET",url,true);
 5     xmlhttp.onreadystatechange = function(){
 6     if(xmlhttp.readyState == 4){
 7             var msg = xmlhttp.responseText;
 8             if(msg == \'1\'){
 9                 alert(\'用户名或密码错误!!\');
10                 form.password.select();
11                 form.check.value = \'\';
12                 code(form);
13                 return false;
14             }if(msg == "3"){
15                 alert("用户名被占用，请重新输入！");
16                 return false;
17             }else{
18                 alert(\'欢迎光临\');
19                 location.reload();
20             }
21         }
22     }
23     xmlhttp.send(null);
24     return false;