with if?

gistfile1.txt

    $.getJSON('media/js/markers.json', function(data){
        $.each(data.markers, function(i, marker){
            if (...) {
                map.addMarker({
                    id: i,
                    tags: marker.tag,
                    lat: marker.latitude,
                    lng: marker.longitude,
                    infoWindow: {
                        content: '<h2>' + marker.name + '</h2><p>' + marker.address + '</p>'
                    }
                });
            }
        });
    });