<span style="font-size:14px;">    var xmlhttp = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
      xmlhttp.open("POST", "AJAXTest.ashx?" + "i=5&j=10", true);
      xmlhttp.onreadystatechange = function ()
      {
        if (xmlhttp.readyState == 4)
        {
          if (xmlhttp.status == 200)
          {
            alert(xmlhttp.responseText);
          }
          else
          {
            alert("AJAX服务器返回错误！");
          }
        }
      }
      xmlhttp.send(); 


</span>

<span style="font-family:Times New Roman;font-size:14px;">     function ajax(url,onsuccess,onfail)
    {
      var xmlhttp = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
      xmlhttp.open("POST", url, true);
      xmlhttp.onreadystatechange = function ()
      {
        if (xmlhttp.readyState == 4)
        {
          if (xmlhttp.status == 200)
          {
            onsuccess(xmlhttp.responseText);//成功时逻辑操作
          }
          else
          {
            onfail(xmlhttp.status);//失败是逻辑操作
          }
        }
      }
      xmlhttp.send(); //这时才开始发送请求
    }</span>

function Submit1_onclick() {
      var name = document.getElementById("name").value;
      var psw = document.getElementById("psw").value;
      if (psw != "" && name != "") { 
       //调用AJAX
       ajax("../userhandle.ashx?operate=login&userName=" + name + "&psw=" + psw, function (resText) {
          if (resText == "fail") {
            alert("用户名或密码错误！");
            return false;
          }
          else {
            document.write(resText);
          }
        })
      }
      else {
        alert("请输入完整登陆信息！");
        return false;
      }
    }

 public void login(HttpContext context)
    {
      userBLL ub = new userBLL（）；
      string userName = context.Request["userName"];
      string userPsw = context.Request["psw"];   
      bool b = ub.Login(userName, userPsw);//封装好的bll层方法，判断用户名密码是否正确
      if (b == true)
      {
        context.Session["Name"] = userName;
        context.Session["role"] = "user";
        context.Response.Write("success");
       }
      else
      {
        context.Response.Write("fail");
      }
    }

function check() {
      var userName = document.getElementById("Text1").value;
      if (userName == "" || userName == null) {
        document.getElementById("nameMeg").style.color = "red";
        document.getElementById("nameMeg").innerHTML = "用户名为6-10位英文或数字";
      }
      else { 
      ajax("../userhandle.ashx?operate=checkName&userName=" + userName, function (resText) {
        if (resText == "forbid") {
          document.getElementById("nameMeg").style.color = "red";
          document.getElementById("nameMeg").innerHTML = "用户名含有非法词语";
        } else if (resText == "already have") {
          document.getElementById("nameMeg").style.color = "red";
          document.getElementById("nameMeg").innerHTML = "用户名已被使用";
        } else {
          document.getElementById("nameMeg").style.color = "green";
          document.getElementById("nameMeg").innerHTML = "可以使用";
        }
      })
      }
    }