function readCookie(name) {
  if(document.cookie.length == 0)
    return null;
  var ca = document.cookie.split(';');
  for(var i = 0; i < ca.length; i++) {
    var pair = ca[i].split('=');
    var nme = pair[0].replace(/^\s+|\s+$/g, '');
    var val = pair[1].replace(/^\s+|\s+$/g, '');
    if(nme == name)
      return val;
  }
  return null;
}

function deleteCookie(name) {
  var d = new Date();  // current date & time
  d.setTime(d.getTime() - (60*60*24*365) );
  var expires = d.toGMTString();

  document.cookie = name + "=" +
    ";expires="+expires;
}