2008-02-22 Event.observeに引数 javascript 参考 http://d.hatena.ne.jp/n314/20070116/1168936382 http://weblog.metareal.org/2007/09/02/prototype-1-6-0-event-overhaul-release/ http://www.akatsukinishisu.net/itazuragaki/js/bindaseventlistener.html