function createCookie(name,value,days) {
  if (days) {
    var date = new Date();
    date.setTime(date.getTime() + (days*24*60*60*1000));
    var expires = "; expires=" + date.toGMTString();
  }
  else var expires = "";
  document.cookie = name + "=" + escape(value) + expires + "; path=/";
}

function readCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for(var i=0;i < ca.length; i++) {
    var c = ca[i];
    while (c.charAt(0)==' ') c = c.substring(1,c.length);
    if (c.indexOf(nameEQ) == 0) return unescape(c.substring(nameEQ.length, c.length));
  }
  return null;
}

function eraseCookie(name) {
  createCookie(name, "", -1);
}