Determine the existence of a key in a cookie ?

[tangyi]

i'm trying to figure out how to determine the existence of a specfic key in a collection cookie.
anyone has any ideas on how to do this?
thanks.

 

[rac2]

function getCookie(name){
   var cname = name + "=";
   var dc = document.cookie;
   if(dc.length > 0){
      begin = dc.indexOf(cname);
      if(begin != -1){
         begin += cname.length;
         end = dc.indexOf(";", begin);
         if(end == -1) end = dc.length;
         return unescape(dc.substring(begin,end));
      }
   }
   return null;
}

From Heinle, Designing with Javascript: Creating Dynamic Web Pages.