<script type="text/javascript">

         window.onload = function () {

             document.getElementById("btn").onclick = function () {

                 var username = document.getElementById("uname").value;

                 var password = document.getElementById("pwd").value;

                 var xmh = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");

                 xmh.open("post", "/Handler1.ashx?username=" + username + "&password=" + password, true);

                 xmh.onreadystatechange = function () {

                     if (xmh.readyState == 4) {

                         if (xmh.status == 200) {

                             //var x=eval('('+xmh.responseText+')');//把json字符串转换为json对象

                                                                     //上下两种方法都行

                             var x = JSON.parse(xmh.responseText);//把json字符串转换为json对象

                             alert(x.status);

                         }

                         else {

                             alert("出错");

                         }

                     }

                 };

                 xmh.send();

             }

         };

     </script>