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); // trim?
  if (c.indexOf (nameEQ) == 0) return c.substring (nameEQ.length, c.length);
 }
 return null;
}

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 + "=" + value + expires + "; path=/";
}

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