var chap_array = new Array(
    ["9 - Extras",'9'],

    ["8 - Akane-chan OVER DRIVE 2 Vol3",'8'],

    ["7 - Akane-chan OVER DRIVE 2 Vol2",'7'],

    ["6 - Akane-chan OVER DRIVE 2 Vol1",'6'],

    ["5 - Akane-chan Say Goodbye",'5'],

    ["4 - Hyponotic Warrior Akira-kun",'4'],

    ["3 - Akane-chan PANIC ATTACK",'3'],

    ["2 - Akane-chan Non Stop",'2'],

    ["1 - Akane-chan OVER DRIVE",'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]);
    }
}