遮罩层

<style>
    #BgDiv{
        width:100%;
        height:100%;
        background-color: rgba(0,0,0,0.05);
        opacity: 0.3;

    }
</style>

<div id="BgDiv" style="display: none;"></div>

关闭按钮加class  .click-close-hide
点击显示按钮  #newQuestionBtn  和#addTable

<script>
   //  遮罩层显示隐藏
   //点击增加让出现遮罩层
   $('body').on('click','#addTable',function(){
       $('#BgDiv').show();
       $('#BgDiv').css("z-index","1000");
   })

    //点击新增问题让出现遮罩层，同时让增加的弹框隐藏
   $('body').on('click','#newQuestionBtn',function(){
       $('#BgDiv').show();
        $('#BgDiv').css("z-index","1000");
       $('.modal-dialog.modal-lg .modal-content ').hide();
   })
  $('body').on('click','.click-close-hide',function(){
         $('#BgDiv').hide();
          $('.modal-dialog.modal-lg .modal-content ').show();
         $('#BgDiv').css("z-index","-1");
     })
   </script>