function add12DaySelected() {
  var date = addDate(12);

  var year = date.getFullYear();
  var month = date.getMonth();
  var day = date.getDate();
  var yearObj = document.getElementById("year");
  if(year = 2012) {
    yearObj.selectedIndex = 0;
  }
  else if(2013) {
    yearObj.selectedIndex = 1;
  }

  var monthObj = document.getElementById("month");
  monthObj.selectedIndex = month;
  var dayObj = document.getElementById("day");
  dayObj.selectedIndex = day -1;

}

function addDate(addDays) {
  var today = new Date();

  var year = today.getFullYear();
  var month = today.getMonth();
  var day = today.getDate();

  var dt = new Date(year, month, day);

  var baseSec = dt.getTime();
  var addSec = addDays * 86400000;
  var targetSec = baseSec + addSec;
  dt.setTime(targetSec);
  return dt;
}

function search() {

  var year = document.getElementById("year").selectedIndex + 2012;
  var month = document.getElementById("month").selectedIndex + 1;
  var day = document.getElementById("day").selectedIndex + 1;

  var url = "http://www.tabitora.co.jp/tiger-front/view/info/planList.html?"
            + "h=738" 
            + "&y=" + year
            + "&m=" + month
            + "&d=" + day
            + "&st=1"
            + "&cn=0"
            ;

  window.open(url);
}