var chap_array = new Array(
    ["17 - Mythology of the Shooting Star - Part 3",'17'],

    ["16 - Mythology of the Shooting Star - Part 2",'16'],

    ["15 - Mythology of the Shooting Star - Part 1",'15'],

    ["14 - Blue Sky of Promise - Part 2",'14'],

    ["13 - Blue Sky of Promise - Part 1",'13'],

    ["12 - Roaming Thunderclap - Part 2",'12'],

    ["11 - Roaming Thunderclap - Part 1",'11'],

    ["10 - Destroyer of the Jungle - Part 2",'10'],

    ["9 - Destroyer of the Jungle - Part 1",'9'],

    ["8 - Ocean of Machine-Armor - Part 2",'8'],

    ["7 - Ocean of Machine-Armor - Part 1",'7'],

    ["6 - Memories of the Right Arm",'6'],

    ["5 - Pride of Hot Sand - Part 2",'5'],

    ["4 - Pride of Hot Sand - Part 1",'4'],

    ["3 - One Man Battle - Part 2",'3'],

    ["2 - One Man Battle - Part 1",'2'],

    ["1 - Skyscraper's Gale",'1']
);
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]);
    }
}