<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script src="/libs/jquery-levelup/jquery.levelup.min.js"></script>

<span>counter <span style="font-weight: bold;" id='the_cnt'>0</span></span>

<script>
    var $tc = $('#the_cnt');
    $tc.levelup({'start' : 0});

    $('#incrementBtn').on('click', function(event) {
        $tc.levelup('increment', 1);
        $(this).blur();
    });
    $('#decrementBtn').on('click', function(event) {
        $tc.levelup('decrement', 1);
        $(this).blur();
    });
</script>