Try this code (demo), it uses the filterEnd
event to update the row count display:
var $count = $('.count'),
$t = $('table'),
$tr = $t.find('tbody tr'),
update = function(){
var t = $tr.filter(':visible').length + '/' + $tr.length;
$count.html(t);
};
$t
.on('filterEnd', function () {
update();
})
.tablesorter({
theme: 'blue',
widgets: ['zebra', 'filter'],
initialized: function(){
update();
}
});