为什么表页脚不出现

Question

我正在尝试对jquery数据表中的列进行总计，但表页脚未出现

总计出现在控制台中，并且总计在过滤器或搜索中发生了变化。

但是表在初始化后没有页脚标记

我不确定表初始化是否在footerCallback之前调用

该表工作正常，并且计算了总数，但是我认为这一切都发生在表初始化之前。这是正确的

如果我正确，则需要进行哪些更改？

 var table = $('#resultstable').DataTable( 
 {
 fixedHeader: {
    footer: true,
        footerOffset: 40
           },
           "paging": false,
           "info":false,
           "stateSaving":true,
           "searching":true,
           "order": [[ 1, "asc" ]],
           data:tabledata,
           columnsDef:[
           {
               "targets":[2],
                ClassName:"sum"
           }],
           columns:[
                    {
                        className:'details-control',
                        orderable:false,
                        data:null,
                        defaultContent: '',

                     },
                     {                       
                        orderable:true,
                        className:"packName",
                        title:"Name : "
                     },
                     {
                        className:'sum',
                        orderable:true,
                        title:"Total : ",
                     },
                     {
                        className:'sum',
                        title:"Passed : ",
                        orderable:true,

                     },
                     {
                        className:'sum',
                        title:"Failed ",
                        orderable:true,
                     },
                     {
                        className:'sum',
                        title:"New Failures ",
                       'orderable':true
                     }
                       ],
                     "fnCreatedRow": function( nRow, aData, iDataIndex )
                     {
                      $(nRow).attr('value', aData[(aData.length-1)]);
                     },
                     "initComplete": function(settings, json)
                     {

                     },
            "footerCallback":function(row, data, start, end,display)
            {
                var api = this.api();
                var cols = api.columns('.sum',{search:'applied'}); 
                cols.every(function(){
                       var sum = this
                           .data()
                           .reduce(function(a,b){
                           var x = parseFloat(a) || 0;
                           var y = parseFloat(b) || 0;
                           return x + y;
                       },0);
                       console.log(sum); 
                       $(this.footer()).html(sum);

                       });
                       }
  } );