DataTables - Child rows

HTML

<link rel="stylesheet" href="https://cdn.datatables.net/r/dt/dt-1.10.9/datatables.min.css">
<script src="https://cdn.datatables.net/r/dt/dt-1.10.9/datatables.min.js"></script>
<table id="example" class="display" cellspacing="0" width="100%">
    <thead>
        <tr>
            <th></th>
            <th>Name</th>
            <th>Position</th>
            <th>Office</th>
            <th>Salary</th>
            <th>Extn.</th>
        </tr>
    </thead>
    <tfoot>
        <tr>
            <th></th>
            <th>Name</th>
            <th>Position</th>
            <th>Office</th>
            <th>Salary</th>
            <th>Extn.</th>
        </tr>
    </tfoot>
</table>

CSS

td.details-control {
    background: url('https://raw.githubusercontent.com/DataTables/DataTables/1.10.7/examples/resources/details_open.png') no-repeat center center;
    cursor: pointer;
}
tr.shown td.details-control {
    background: url('https://raw.githubusercontent.com/DataTables/DataTables/1.10.7/examples/resources/details_close.png') no-repeat center center;
}


table.dataTable .child-container table
{
  width: 47%;
  margin:10px 10px 10px 40px;
  float:left;
  border: solid 1px #dddddd;
}

table.dataTable .child-container {
  max-height: 150px;
  overflow-y: auto;
}

JavaScript

/* Formatting function for row details - modify as you need */
function format ( d ) {
    // `d` is the original data object for the row
    return '<div class="child-container">'+
        '<table cellpadding="5" cellspacing="0" border="0">'+
            '<tr>'+
                '<td>Full name:</td>'+
                '<td>'+d.name+'</td>'+
            '</tr>'+
            '<tr>'+
                '<td>Extension number:</td>'+
                '<td>'+d.extn+'</td>'+
            '</tr>'+
            '<tr>'+
                '<td>Extra info:</td>'+
                '<td><button>Click Me</button></td>'+
          
            '</tr>'+
        '</table>'+
        '<div id="myDIV" style="display:none">Toggle content</div>' +
    '</div>';
}

$(document).ready(function() {
    var table = $('#example').DataTable( {
        "ajax": 'https://api.myjson.com/bins/16lp6',
        "columns": [
            {
                "class":          'details-control',
                "orderable":      false,
                "data":           null,
                "defaultContent": ''
            },
            { "data": "name" },
            { "data": "position" },
            { "data": "office" },
            { "data": "salary" },
            { "data": "extn", "visible": false }
            
        ],
        "order": [[1, 'asc']]
    } );

    // Add event listener for opening and closing details
    $('#example tbody').on('click', 'td', function () {
        var tr = $(this).closest('tr');
        var row = table.row( tr );

        if ( row.child.isShown() ) {
            // This row is already open - close it
            row.child.hide();
            tr.removeClass('shown');
        }
        else {
            // Open this row
            row.child( format(row.data()), 'no-padding' ).show();
            tr.addClass('shown');

        }
    } );
    
    $('#example tbody').on('click', 'td > button', function (e) {
//       alert('Tada!');
       var x =...