JSFiddle - React, Tailwind, and code Playground

HTML

<div class="table_div" style="float: left; width: 99%; overflow-x: auto">
                            <table id="example" class="display Bil" cellspacing="0" width="100%" style="font-family: Arial;
                                overflow-x: scroll; width: 1336px; font-size: small; font-weight: normal; border-collapse: collapse;
                                white-space: nowrap; clear: both;">
                                <thead id="HEADER">
                                </thead>
                                <tbody id="tblempDetails" class="alignfields">
                                </tbody>
                                <tfoot id="FOOTER">
                                </tfoot>
                            </table>
                        </div>

JavaScript

table = $('#example').DataTable({
                responsive: true,
                columnDefs: [
            { responsivePriority: 1, targets: 0 },
            { responsivePriority: 2, targets: -2 }
        ],
                paging: true,
                searching: false,
                //            processing: true,        
                dom: 'Bfrtip',
                buttons: ['colvis', { extend: 'excel', exportOptions: { columns: ':visible' }, title: $("#ctl00_ContentPlaceHolder1_lblPageName").text(),
                    customize: function (xlsx) {
                        var sheet = xlsx.xl.worksheets['sheet1.xml'];
                        var numrows = 7;
                        debugger;
                        var mergeCells = $('mergeCells', sheet);
                        mergeCells[0].appendChild(_createNode(sheet, 'mergeCell', {
                            attr: {
                                ref: 'A1:E1'
                            }
                        }));

                        mergeCells.attr('count', mergeCells.attr('count') + 1);


                        function _createNode(doc, nodeName, opts) {
                            var tempNode = doc.createElement(nodeName);

                            if (opts) {
                                if (opts.attr) {
                                    $(tempNode).attr(opts.attr);
                                }

                                if (opts.children) {
                                    $.each(opts.children, function (key, value) {
                                        tempNode.appendChild(value);
                                    });
                                }

                                if (opts.text !== null && opts.text !== undefined) {
                                    tempNode.appendChild(doc.createTextNode(opts.text));
                                }
                            }

                            return tempNode;
                      ...