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 = http://www.mamicode.com/‘‘;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;