function smartRollover() {
if(document.getElementsByTagName) {
var images = document.getElementsByTagName("img");

for(var i=0; i < images.length; i++) {
if(images[i].getAttribute("src").match("_off."))
{
images[i].onmouseover = function() {
this.setAttribute("src", this.getAttribute("src").replace("_off.", "_on."));
}
images[i].onmouseout = function() {
this.setAttribute("src", this.getAttribute("src").replace("_on.", "_off."));
}
}
}
}
}

if(window.addEventListener) {
window.addEventListener("load", smartRollover, false);
}
else if(window.attachEvent) {
window.attachEvent("onload", smartRollover);
}

function getRequest(){
  if(location.search.length > 1) {
    var get = new Object();
    var ret = location.search.substr(1).split("&");
    for(var i = 0; i < ret.length; i++) {
      var r = ret[i].split("=");
      get[r[0]] = r[1];
    }
    return get;
  } else {
    return false;
  }
}

function WriteCookie(key, value, days) {
     var str = key + "=" + escape(value) + ";";         // 書き出す値１ : key=value
     if (days != 0) {                                                 /* 日数 0 の時は省略 */
          var dt = new Date();                                   // 現在の日時
          dt.setDate(dt.getDate() + days);                   // days日後の日時
          str += "expires=" + dt.toGMTString() + ";"; // 書き出す値２ : 有効期限
     }
     document.cookie = str;                                   // Cookie に書き出し
}

function track(){
  var g =getRequest();
  if(g['ref']){
    WriteCookie('ref', g['ref'],2);
  }
}