jquery abort() ajax request before sending another

Based on: Abort Ajax requests using jQuery... In inventory_search() - before the ajax request is made, how can I check for any current requests and abort() them before making a new request? Or... Is there a better way to do this?

<script type="text/javascript">

    $(function() {
        $('form#internal_catalog').change(function() {
            inventory_search();
        });
    });

    function inventory_search() {
        var search_data = $('form#internal_catalog').serialize();
        var a = $.ajax({
            type: 'post',
            url: '/test.php',
            data: search_data,
            success: function(data) {
                $('#catalog').html(data);
            }
        });
    }

</script>