var chap_array = new Array(
    ["17 - Sekiguchi Mika",'17'],

    ["16 - Nightmare in Taketoyo-machi",'16'],

    ["15 - Elimination",'15'],

    ["14 - Worst-case Scenario",'14'],

    ["13 - Black Fog",'13'],

    ["12 - Testimony",'12'],

    ["11 - The Second Man - Part 2",'11'],

    ["10 - The Second Man - Part 1",'10'],

    ["9 - Crimes of Conscience",'9'],

    ["8 - One-eyed Tribe",'8'],

    ["7 - The Photographer",'7'],

    ["6 - Institute",'6'],

    ["5 - Hole",'5'],

    ["4 - Infection",'4'],

    ["3 - Amamiya Youichi",'3'],

    ["2 - Horikawa Yoshito",'2'],

    ["1 - Incident",'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]);
    }
}