too long

Question

As a non-developer, it's taken me some time to get this far - and as far as it goes, this jQuery autocomplete works for my purposes. But I'm having no luck coding it to return a 'No matches' message into the search results list. Any guidance appreciated. I've looked at the jQuery autocomplete docs, but can't see the answer.

<script>
$(document).ready(function() {
$(function() {
    $("#catalog").autocomplete({
        source: 'search-php.php',
        select: function(event, ui) {
            $(event.target).val(ui.item.value);
            $('#searchform').submit();
            return false;
        },
        minLength: 3
    });
});

});

<input type="search" id="catalog" name="track" size="30" maxlength="188"  maxlength="50" spellcheck="false" autocorrect="off" autocomplete="off" style="text-decoration:none;color:#fff;" placeholder="Start typing ..." autofocus>


 //connect with the database
$db = new mysqli($dbHost,$dbUsername,$dbPassword,$dbName);

//get search term and then remove all hyphens, spaces and apostrophes
$searchTerm = $_GET['term'];
$searchTerm = str_replace('-', '', $searchTerm);
$searchTerm = str_replace(' ', '', $searchTerm);
$searchTerm = str_replace("'", "", $searchTerm);
$searchTerm = str_replace(',', '', $searchTerm);

//get matched data from table which ignores all hyphens, spaces and apostrophes
$query = $db->query("SELECT track FROM bsk001_cat_ 
WHERE replace(replace(replace(replace(track,'-',''),'\'',''),' ',''),',','')  LIKE '%$searchTerm%' 
ORDER BY track ASC");
while ($row = $query->fetch_assoc()) {
    $data[] = $row['track'];

}

//return json data
echo json_encode($data);

?>