var chap_array = new Array(
    ["18 - Escape 7",'18/01'],

    ["17 - Escape 6",'17/01'],

    ["16 - Escape 5",'16/01'],

    ["15 - Escape 4",'15/01'],

    ["14 - Escape 3",'14/01'],

    ["13 - Escape 2",'13/01'],

    ["12 - Escape 1",'12/01'],

    ["11 - Rotation 5",'11/01'],

    ["10 - Rotation 4",'10/01'],

    ["9 - Rotation 3",'9/00'],

    ["8 - Rotation 2",'8/01'],

    ["7 - Rotation 1",'7/01'],

    ["6 - Ripple 6",'6/01'],

    ["5 - Ripple 5",'5/01'],

    ["4 - Ripple 4",'4/01'],

    ["3 - Ripple 3",'3/01'],

    ["2 - Ripple 2",'2/01'],

    ["1 - Ripple 1",'1/00']
);
for (var i=0; i<chap_array.length; i++) {
    document.getElementById('id_chapter_1').options[i] = new Option(chap_array[i][0],chap_array[i][1]);
    if (document.getElementById('id_chapter_2')) {
        document.getElementById('id_chapter_2').options[i] = new Option(chap_array[i][0],chap_array[i][1]);
    }
}