//It is convenient to define functions to perform these tasks. Here, for example, is a function that sets cookie values and expiration:

function setCookie(name, value, expiredays, path, domain, secure) {
   if (expiredays) {
      var exdate=new Date();
      exdate.setDate(exdate.getDate()+expiredays);
      var expires = exdate.toGMTString();
   }
   document.cookie = name + "=" + escape(value) +
   ((expiredays) ? "; expires=" + expires : "") +
   ((path) ? "; path=" + path : "") +
   ((domain) ? "; domain=" + domain : "") +
   ((secure) ? "; secure" : "");
}

//Notice the use of escape to encode special characters (semicolons, commas, spaces) in the value string. This function assumes that cookie names do not have any special characters.The following function returns a cookie value, given the name of the cookie:

function getCookie(Name) {
   var search = Name + "="
   if (document.cookie.length > 0) { // if there are any cookies
      offset = document.cookie.indexOf(search) 
      if (offset != -1) { // if cookie exists 
         offset += search.length 
         // set index of beginning of value
         end = document.cookie.indexOf(";", offset) 
         // set index of end of cookie value
         if (end == -1) 
            end = document.cookie.length
         return unescape(document.cookie.substring(offset, end))

      } 
   }
}