.net Ajax使用

function CheckUsername() {        var strName = $("#txtUserName").val();        $.ajax({
            type: "GET",  //请求方式            async: false, //false为同步            url: "../../xx/xxx.ashx?action=xxx",            data: { param: strName },//传递的参数            success: function (msg) {                var obj = JSON.parse(msg); //解析json格式的数据
                if (obj.status == "n") {                    document.getElementById("btnSubmit").disabled = true;                    $("#spanName").html(obj.info).css({ color: "red" });
                } else {                    $("#spanName").html(obj.info).css({ color: "black " });                }            }        });    }