// 添加以下代码来进行测试：
 // ajax 发生错误，就会执行
$('body').ajaxError(function(e, xhr, setting, text){
    // e - event 事件
    // xhr - XMLHttpRequest 对象
    // setting - ajax 设置
    // text - 错误信息
    alert(text);
});
 
// ajax 完成后，就会执行
$('body').ajaxComplete(function(){
    alert('complete'); // ajax 请求完成就会执行
})

//同步请求，锁住浏览器
 $.ajax({
        url: '/sms/AjaxSMS.ashx',
        type: "POST",
        data: "txtcontent=" + content+"&txtback=" + content2+"",
        async: false, 
        dataType:"json",
        success: function(data) {

            if (data == "成功" || data == "[object XMLDocument]") {
                IsAddSuffix(hdtatolSMS, arr, mob); //后缀名
                confirm("您本次发送短信数量为：" + (parseInt(hdtatolSMS) * arr.length) + ",确认发送吗？");
            } else {
                alert(content + "可能涉及广告类、营销类等系统不允许发送的内容，请修改后再发送。");
            }
        },
        error: function(a) {
            alert(a.responseText);
        }
    });

//添加后缀判断
function IsAddSuffix(data, arr, mob) {
    var txtBack = document.getElementById("ctl00_ContentPlaceHolder1_txtBack").value;
    if (txtBack == "") {
        confirm("后缀为空，您本次发送短信数量为：" + (parseInt(data) * arr.length) + ",确认发送吗？");
    } else {
        if (txtBack.length + mob.value.length > maxnums - 1) {
            alert("内容加上后缀(系统自动补充空格)长度不能起过" + maxnums + "个字符，请重新输入!");
        }
    }
}

<script type="text/javascript" language="javascript">
        $(function() {
            //弹出提示框（快旅新域名）
            var isRead = getHCookie('warnTips');
            if (isRead == null) {
                popupDiv('pop-div');
            }

function popupDiv(div_id) {
                var div_obj = $("#" + div_id);
                var windowWidth = document.documentElement.clientWidth;
                var windowHeight = document.documentElement.clientHeight;
                var popupHeight = div_obj.height();
                var popupWidth = div_obj.width();
                //添加并显示遮罩层  
                $("<div id='mask'></div>").addClass("mask")
                .width(windowWidth * 0.99)
                .height(windowHeight * 0.99)
                //.css({ "position": "absolute", "background": "#CCCCCC", "left": "0px", "top": "0px", "zIndex": "1", "filter": "Alpha(Opacity=60)" })遮盖层
                .css({ "position": "absolute" })
                .click(function() { hideDiv(div_id); })
                .appendTo("body")
                .fadeIn(200);
                div_obj.css({ "position": "absolute" })
                .animate({ left: windowWidth / 2 - popupWidth / 2,
                    top: windowHeight / 2 - popupHeight / 2, opacity: "show"
                }, "slow");
            }

});
        function hideDiv(div_id) {
            $("#mask").remove();
            $("#" + div_id).animate({ left: 0, top: 0, opacity: "hide" }, "slow");
            //记录cookie
            SetHCookie('warnTips', 'read');
            //window.parent.del();
        }

function SetHCookie(name, value)//两个参数，一个是cookie的名称，一个是值
        {
            var Days = 1; //此 cookie 将被保存 1 天 
            var exp = new Date();
            exp.setTime(exp.getTime() + Days * 24 * 60 * 60 * 1000);
            document.cookie = name + "=" + escape(value) + ";expires=" + exp.toGMTString();
        }
        function getHCookie(name)//取cookies函数         
        {
            var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
            if (arr != null) return unescape(arr[2]); return null;
        }
        function delHCookie(name)//删除cookie 
        {
            var exp = new Date();
            exp.setTime(exp.getTime() - 1);
            var cval = getHCookie(name);
            if (cval != null) document.cookie = name + "=" + cval + ";expires=" + exp.toGMTString();
        }
  </script>

z-index遮罩层的光标输入方案：遮罩层问题。必须设置z-index，必须小于父div元素的数值，不然会失去效果。