ボタン押しっぱなし

scroll_up_and_down_button.erb

<div id="scroller_up"><%= image_tag 'btn_up.jpg' %></div>
<div id="scroller_down"><%= image_tag 'btn_down.jpg' %></div>
  
<%= javascript_tag do %>
  var scroll_up_flg = true;
  var scroll_down_flg = true;
  Event.observe('scroller_up', 'mousedown', scroll_up_start);
  Event.observe('scroller_up', 'mouseup', scroll_up_off);
  Event.observe('scroller_down', 'mousedown', scroll_down_start);
  Event.observe('scroller_down', 'mouseup', scroll_down_off);

  // ▲フラグon
  function scroll_up_start(){
    scroll_up_flg = true;
    var timerID = setInterval(function(){scroll_up_flg ? scroll_up() : clearInterval(timerID)}, 100);
  }
  // ▲フラグoff
  function scroll_up_off(){
    scroll_up_flg = false;
  }
  // ▲スクロール
  function scroll_up(){
    $('ici_frame').scrollTop -= <%= Setting.scroll_count %>;
  }
  
  // ▼フラグon
  function scroll_down_start(){
    scroll_down_flg = true;
    var timerID = setInterval(function(){scroll_down_flg ? scroll_down() : clearInterval(timerID)}, 100);
  }
  // ▼フラグoff
  function scroll_down_off(){
    scroll_down_flg = false;
  }
  // ▼スクロール
  function scroll_down(){
    $('ici_frame').scrollTop += <%= Setting.scroll_count %>;
  }
  
<% end %>