<script>
    var counter = 1;

    $(".forrige").click(forrige);
    $(".næste").click(skiftbilled);

    function skiftbilled() {
        counter++;
        $("iframe").attr("src","pages/scene"+counter+".html")

    }

    function forrige() {
        counter--;
        $("iframe").attr("src","pages/scene"+counter+".html")
    }

    var counter= 1;

</script>