<script>

var alertmessage="检测到您当前浏览器为IE8或以下版本，建议您使用IE9或以上版本，或者火狐、谷歌浏览器，才能体验到最佳效果"

var once_per_session=

function get_cookie(Name) {

  var search = Name + "="

  var returnvalue = "";

  if (document.cookie.length > ) {

    offset = document.cookie.indexOf(search)

    if (offset != -) {

      offset += search.length

      end = document.cookie.indexOf(";", offset);

      if (end == -)

         end = document.cookie.length;

      returnvalue=unescape(document.cookie.substring(offset, end))

      }

   }

  return returnvalue;

}

function alertornot(){

if (get_cookie('alerted')==''){

loadalert()

document.cookie="alerted=yes"

}

}

function loadalert(){

alert(alertmessage)

}

if (once_per_session==)

loadalert()

else

alertornot()

</script>