function getCookie (name) {  
  var arg = name + "=";  
  var alen = arg.length;  
  var clen = document.cookie.length;  
  var i = 0;  
  var endstr = 0;
  while (i < clen) {
    var j = i + alen;    
    if (document.cookie.substring(i, j) == arg) {
      endstr = document.cookie.indexOf (";", j);
      if (endstr == -1) endstr = document.cookie.length;
      return unescape(document.cookie.substring(j, endstr));
    }    
    i = document.cookie.indexOf(" ", i) + 1;    
    if (i == 0) break;   
  }  
  return null;
}

function setCookie (name, value) {  
  var argv = setCookie.arguments;  
  var argc = setCookie.arguments.length;  

  //
  // default expiration:
  //
  //var expires = (argc > 2) ? argv[2] : null;  

  //
  // 30-day expiration:
  //
  var expires = new Date();
  expires.setTime(expires.getTime() + (30*24*60*60*1000));

  var path    = (argc > 3) ? argv[3] : null;  
  var domain  = (argc > 4) ? argv[4] : null;  
  var secure  = (argc > 5) ? argv[5] : false; 
  document.cookie = name + "=" + escape (value) + 
  ((expires == null) ? "" : ("; expires=" + expires.toGMTString())) + 
  ((path == null)    ? "" : ("; path=" + path)) +  
  ((domain == null)  ? "" : ("; domain=" + domain)) +    
  ((secure == true)  ? "; secure" : "");
}

function deleteCookie (name) {  
  var exp = new Date();  
  exp.setTime (exp.getTime() - 1);   
  var cval = getCookie (name);  
  document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString();
}