$(button).click(function(){
    $(div).show();
    $.ajax({
        url: "xxx",
        ...
        complete: function({
            $(div).hide();
        });
    });
});

------解决方案--------------------
JScript code

 $.ajax({
           url: url,
            ....
            beforeSend: function () {
               div弹出层显示等待
            },
            complete: function () {
              隐藏div
            },
            success: function (result) {
                
            },
            error: function (result, b) {
               错误提示
            }
        });