var chapter_list = new Array(
  ["Vol.01 Ch.001.1: Meeting Him","v01/c001.1"],
  ["Vol.01 Ch.001.2: Meeting him","v01/c001.2"],
  ["Vol.01 Ch.002: Han Hyewon Gets Bullied","v01/c002"],
  ["Vol.02 Ch.001","v02/c001"],
  ["Vol.02 Ch.002: Bin's Story","v02/c002"],
  ["Vol.02 Ch.003: Trouble","v02/c003"],
  ["Vol.02 Ch.004: Twisted Encounter with Hyun Si-woo","v02/c004"],
  ["Vol.03 Ch.001: Painful Past","v03/c001"],
  ["Vol.03 Ch.002: At The Club","v03/c002"],
  ["Vol.03 Ch.003: Crossed Paths","v03/c003"],
  ["Vol.04 Ch.001","v04/c001"],
  ["Vol.04 Ch.002: Confused Hearts","v04/c002"],
  ["Vol.04 Ch.003: Hurt Souls","v04/c003"],
  ["Vol.04 Ch.004: Please hold onto me","v04/c004"],
  ["Vol.04 Ch.005: You Are Mine","v04/c005"],
  ["Vol.05 Ch.001: Sleepless Night","v05/c001"],
  ["Vol.05 Ch.002: What's happening?!","v05/c002"],
  ["Vol.05 Ch.003: Trap","v05/c003"],
  ["Vol.05 Ch.004: end","v05/c004"]
);

var total_chapters = 19;

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;