var chapter_list = new Array(
  ["Vol.01 Ch.000: 1: A, A' \ 2: 4/4 (Quarte-Quarts) \ 3: X+Y Part 1 \ 4: X+Y Part 2","v01/c000"]
);

var total_chapters = 1;

for (var i = 0; i < chapter_list.length; i++) {
  document.getElementById('top_chapter_list').options[i] = new Option(chapter_list[i][0], chapter_list[i][1]);
  document.getElementById('bottom_chapter_list').options[i] = new Option(chapter_list[i][0], chapter_list[i][1]);
}
document.getElementById('top_chapter_list').value=current_chapter;
document.getElementById('bottom_chapter_list').value=current_chapter;
var current_chapter_index = document.getElementById('top_chapter_list').selectedIndex;