var chapter_list = new Array(
  ["Vol.01 Ch.001: Blend 1 Millionaire's Inheritance","v01/c001"],
  ["Vol.01 Ch.002: Lady Master's Strange Habit","v01/c002"],
  ["Vol.01 Ch.003: A Poindexter's Melancholy","v01/c003"],
  ["Vol.01 Ch.004: New World's Christmas Night","v01/c004"],
  ["Vol.01 Ch.005: An unexpected New Years","v01/c005"],
  ["Vol.02 Ch.006","v02/c006"],
  ["Vol.02 Ch.007","v02/c007"]
);

var total_chapters = 7;

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;