jquery datatables footer column

HTML

<link rel="stylesheet" href="//cdn.datatables.net/1.10.7/css/jquery.dataTables.min.css">
<script src="//cdn.datatables.net/1.10.7/js/jquery.dataTables.min.js"></script>
<link rel="stylesheet" href="//cdn.datatables.net/colvis/1.1.0/css/dataTables.colVis.min.css">
<script src="//cdn.datatables.net/colvis/1.1.0/js/dataTables.colVis.min.js"></script>
<table id="storages"></table>

JavaScript

$.fn.storageTable = function() {
    $(this).append("<tfoot><tr><td></td><td></td></tr></tfoot>")
    return this.dataTable({
        data: dataSet,
        aoColumns: [
            {title: "Name", mData: "name"},
            {title: "Size", mData: "size"}
        ],
        oLanguage: {sEmptyTable: "No logs"},
        fnFooterCallback: function(nRow, aaData, iStart, iEnd, aiDisplay) {
            var api = this.api();
            var size = 0;
            aaData.forEach(function(x) {
                size += (x['size']);
            });
            $(api.column(1).footer()).html(size);        
        }
    });
}

var dataSet = [
    {name: "storage101", size: 492},
    {name: "storage102", size: 742},
    {name: "storage103", size: 423}
]

$.extend($.fn.dataTable.defaults, {
    sDom: '<"top"i>rCt<"bottom"flp><"clear">'
});

$("#storages").storageTable();