/*
 *  name - name of the cookie
 *  value - value of the cookie
 * [expires] - expiration date of the cookie
 *    (defaults to end of current session)
 *  [path] - path for which the cookie is valid
 *    (defaults to path of calling document)
 *  [domain] - domain for which the cookie is valid
 *    (defaults to domain of calling document)
 *  [secure] - Boolean value indicating if the cookie transmission requires
 *    a secure transmission
 *   an argument defaults when it is assigned null as a placeholder
 *   a null placeholder is not required for trailing omitted arguments
 */
function setCookie(name, value, expires, path, domain, secure) {
  var curCookie = name + "=" + escape(value) +
      ((expires) ? "; expires=" + expires.toGMTString() : "") +
      ((path) ? "; path=" + path : "") +
      ((domain) ? "; domain=" + domain : "") +
      ((secure) ? "; secure" : "");
  document.cookie = curCookie;
}

/*
 * name - name of the desired cookie
 *  return string containing value of specified cookie or null
 * if cookie does not exist
 */
function getCookie(name) {
  var dc = document.cookie;
  var prefix = name + "=";
  var begin = dc.indexOf("; " + prefix);
  if (begin == -1) {
    begin = dc.indexOf(prefix);
    if (begin != 0) return null;
  } else
    begin += 2;
  var end = document.cookie.indexOf(";", begin);
  if (end == -1)
    end = dc.length;
  return unescape(dc.substring(begin + prefix.length, end));
}


/*
 *  name - name of the cookie
 *  [path] - path of the cookie (must be same as path used to create cookie)
 *  [domain] - domain of the cookie (must be same as domain used to
 *    create cookie)
 *  path and domain default if assigned null or omitted if no explicit
 *    argument proceeds
 */
function deleteCookie(name, path, domain) {
  if (getCookie(name)) {
    document.cookie = name + "=" +
    ((path) ? "; path=" + path : "") +
    ((domain) ? "; domain=" + domain : "") +
    "; expires=Thu, 01-Jan-70 00:00:01 GMT";
  }
}