JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/datatables/1.10.19/js/jquery.dataTables.min.js"></script>
<script src="https://cdn.datatables.net/rowgroup/1.1.0/js/dataTables.rowGroup.min.js"></script>
<link rel="stylesheet" href="https://cdn.datatables.net/1.10.19/css/jquery.dataTables.min.css">
<link rel="stylesheet" href="https://cdn.datatables.net/rowgroup/1.1.0/css/rowGroup.dataTables.min.css">
<script src="https://cdn.datatables.net/buttons/1.5.6/js/dataTables.buttons.min.js"></script>
<script src="https://cdn.datatables.net/buttons/1.5.6/js/buttons.colVis.min.js"></script>
<link rel="stylesheet" href="https://cdn.datatables.net/buttons/1.5.6/css/buttons.dataTables.min.css">
<table id="example" class="display" style="width:100%">
        <thead>
            <tr>
                <th>Name</th>
                <th>Position</th>
                <th>Office</th>
                <th>Age</th>
                <th>Start date</th>
                <th>Salary</th>
            </tr>
        </thead>
        <tbody>
            <tr>
                <td>Tiger Nixon</td>
                <td>System Architect</td>
                <td>Edinburgh</td>
                <td>61</td>
                <td>2011/04/25</td>
                <td>$320,800</td>
            </tr>
            <tr>
                <td>Garrett Winters</td>
                <td>Accountant</td>
                <td>Tokyo</td>
                <td>63</td>
                <td>2011/07/25</td>
                <td>$170,750</td>
            </tr>
            <tr>
                <td>Ashton Cox</td>
                <td>Junior Technical Author</td>
                <td>San Francisco</td>
                <td>66</td>
                <td>2009/01/12</td>
                <td>$86,000</td>
            </tr>
            <tr>
                <td>Cedric Kelly</td>
                <td>Senior Javascript Developer</td>
               ...

JavaScript

$(document).ready(function() {
    $('#example').DataTable( {
       dom: 'Bfrtip',
        buttons: [
            'colvis'
        ],
       order: [[2, 'asc']],
        rowGroup: {
            startRender: null,
            endRender: function ( rows, group ) {
                var salaryAvg = rows
                    .data()
                    .pluck(5)
                    .reduce( function (a, b) {
                        return a + b.replace(/[^\d]/g, '')*1;
                    }, 0) / rows.count();
                salaryAvg = $.fn.dataTable.render.number(',', '.', 0, '$').display( salaryAvg );
 
                var ageAvg = rows
                    .data()
                    .pluck(3)
                    .reduce( function (a, b) {
                        return a + b*1;
                    }, 0) / rows.count();
 
                return $('<tr/>')
                    .append( '<td colspan="3">Averages for '+group+'</td>' )
                    .append( '<td>'+ageAvg.toFixed(0)+'</td>' )
                    .append( '<td/>' )
                    .append( '<td>'+salaryAvg+'</td>' );
            },
            dataSrc: 2
        }
    } );
} );