I'm putting the dropdown filter in <thead></thead>. But it can't function properly. The search filter in my website works perfectly but not the dropdown filter. I even checked the html code for <option><select> compared to the example in here. When I select one <option>, the table recognizes it as unmatched value, all rows missing.

Here's a screenshot of the table together with html inspector:

Here is my <select> dropdown html code:

<option value=""></option>
<option value="SK Ambong">SK Ambong</option>
<option value="SK Dudar">SK Dudar</option>
<option value="SK Kitou">SK Kitou</option>

Here's my JS code:

$('table').DataTable({
    ordering: false,
    initComplete: function () {
        const nonSearchableColNo = [1, 6, 7, 8];
        var api = this.api();

        // For dropdown column
        api.columns(2).every( function () {
            var column = this;
            var select = $('<select><option value=""></option></select>')
                .appendTo( $(column.header()).empty() )
                .on( 'change', function () {
                    var val = $.fn.dataTable.util.escapeRegex(
                        $(this).val()
                    );

                    column
                        .search( val ? '^'+val+'$' : '', true, false )
                        .draw();
                } );

            column.data().unique().sort().each( function ( data, j ) {
                optionVal = data.match(/SK [A-Z]\w+/g);
                select.append( '<option value="'+optionVal+'">'+optionVal+'</option>' )
            } );
        } );
    }
});