异步请求---Get

前端

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
    <script type="text/javascript">
   
        onload = function () {
            var userName = document.getElementById("tuserName");
            var userPwd = document.getElementById("tuserPwd");
            var btnGet = document.getElementById("btnGet");
            var btnPost = document.getElementById("btnPost");
            var divShow = document.getElementById("divDes");
            btnGet.onclick = function () {
                //发送异步请求
                //1、判断是否IE5 IE6 因为IE5、6只支持ActiveXObject
                var xhr;
                if (XMLHttpRequest) {

                    xhr = new XMLHttpRequest();

                } else {

                    xhr=new ActiveXObject("Microsoft.XMLHTTP")

                }
                //open(method---请求的方法【GET或POSt】,url--请求的页面,asyc 是否异步  ，user请求的用户名，pwd密码 )方法
                //注:Get请求参数通过 地址 来传送，
                var url = "index.ashx?name=" + userName.value + "&password=" + userPwd.value+"&time="+Date.now.toString();
                xhr.open("Get", url, true);
                
                //3、发送异步请求
                xhr.send();


                //4、监听请求状态  onreadystatechange  状态改变事件 4为加载成功
                xhr.onreadystatechange = function () {

                    if (xhr.readyState == 4 && xhr.status == 200)
                    {
                        //如果后台返回成功
                        if (xhr.responseText = "OK") {

                            //location.href = "http://www.baidu.com";
                            divShow.innerHTML = xhr.responseText;

                        }
                        else {

                            divShow.innerHTML = xhr.responseText;

                        }



                    }




                }



            }
            btnPost.onclick = function () {


                alert("btnPost")
            }




        }


    </script>
</head>
<body>
    <input  type="text"  id="tuserName" />
    <input type="text" id="tuserPwd"/>
    <input type="button" id="btnGet" value="btnGet" />
    <input  type="button" id="btnPost" value="btnPost"/>
    <div id="divDes">

    </div>
</body>
</html>

后台

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Ajax练习
{
    /// <summary>
    /// index 的摘要说明
    /// </summary>
    public class index : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "text/html";

            //获取请求到的参数
         string name= context.Request["name"];
         string password = context.Request["password"];


           //执行 处理
         if (name == password)
         {


             //返回结果
             context.Response.Write("OK");

         }
         else
         {  
             //返回结果
             context.Response.Write("NG");
         
         }

        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}