AJAX（get,post）提交数据

 <script type="text/javascript">
        //使用浏览器兼容的方式创建 异步对象
        function createXhr() {
            var xhobj = false;
            try {
                xhobj = new ActiveXObject("Msxml2.XMLHTTP"); // ie msxml3.0+
            } catch (e) {
                try {
                    xhobj = new ActiveXObject("Microsoft.XMLHTTP"); //ie msxml2.6
                } catch (e2) {
                    xhobj = false;
                }
            }
            if (!xhobj && typeof XMLHttpRequest != 'undefined') {// Firefox, Opera 8.0+, Safari
                xhobj = new XMLHttpRequest();
            }
            return xhobj;
        }
        window.onload = function () {
            document.getElementById("btnLogin").onclick = doLoginByGet;
            document.getElementById("btnLoginByPost").onclick = doLoginByPost;
        }
        function doLoginByGet() {
            //获得异步对象
            var xhr = createXhr();
            //设置好参数（请求方式，请求路径，是否启用异步）
            xhr.open("get", "LoginAjax.ashx", true);
            //设置浏览器get方式不使用缓存
            xhr.setRequestHeader("If-Modified-Since","0");
            //设置 异步对象的回调函数--每当异步对象的准备状态发生改变的时候调用
            xhr.onreadystatechange = function () {
                //当readyState==4的时候，就说明 异步对象已经 从服务器获得了返回的数据
                if (xhr.readyState == 4) {
                    //判断服务器返回的状态码是否为200，如果不是，则可能服务器出现了不测
                    if (xhr.status == 200) {
                        //获得异步对象从服务器获得的数据
                        var res = xhr.responseText;
                        alert(res);
                        //获得响应报文头所有信息
                        var hearders = xhr.getResponseHeader("Server");
                        alert(hearders);
                    } else {
                        var hearders = xhr.getResponseHeader("Server");
                        alert(hearders);
                    }
                }
            }
            //让异步对象 发送请求到服务器
            xhr.send(null);
        }
        function doLoginByPost() {
            var xhr = createXhr();
            xhr.open("POST", "LoginAjax.ashx", true);
            xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
            xhr.onreadystatechange = function () {
                if (xhr.readyState == 4) {
                    //判断服务器返回的状态码是否为200，如果不是，则可能服务器出现了不测
                    if (xhr.status == 200) {
                        var res = xhr.responseText;
                        alert("res=" + res);
                    } else {
                        alert("对不起，服务器繁忙，请稍后再试～～～");
                    }
                }
            }
            xhr.send("txtName=jameszou&txtpwd=123");
        }
    </script>