JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://cdn.datatables.net/1.10.16/css/jquery.dataTables.min.css">
<script src="//code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://cdn.datatables.net/1.10.16/js/jquery.dataTables.min.js"></script>
<p>
  People with more than 20 years old: <span id="result"></span>
</p>

<table id="example" class="display" cellspacing="0" 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>
        <tfoot>
            <tr>
                <th>Name</th>
                <th>Position</th>
                <th>Office</th>
                <th>Age</th>
                <th>Start date</th>
                <th>Salary</th>
            </tr>
        </tfoot>
        <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>
                <td>Edinburgh</td>
                <td>22</td>
                <td>2012/03/29</td>
                <td>$433,060</td>
            </tr>
            <tr>
                <td>Airi Satou</td>
               ...

JavaScript

$(document).ready(function() {    
    var table = $('#example').DataTable();
  
    var filteredData = table
        .column(3)
        .data()
        .filter( function ( value, index ) {
            return value > 20 ? true : false;
        } );
        
    document.getElementById('result').textContent = filteredData.count();
    
    document.getElementById('example_filter').addEventListener('keypress', function() {
    document.getElementById('result').textContent = filteredData.count();
    });
} );