function CookieYARAT(adi,degeri,saat)
{

var expires = "";
bitisSuresi = new Date((new Date()).getTime() + saat * 3600000);
bitisSuresi = "; expires=" + bitisSuresi.toGMTString();
document.cookie = adi + "=" + escape(degeri) + bitisSuresi;
return true;
}


function Cookie(adi)
{
var CookieDegeri = "";
var search = adi + "=";
if(document.cookie.length > 0){
tanim = document.cookie.indexOf(search);
if (tanim != -1){
tanim += search.length;
bitis = document.cookie.indexOf(";", tanim);
if (bitis == -1) end = document.cookie.length;
CookieDegeri = unescape(document.cookie.substring(tanim, bitis))
}
}

CookieYARAT("oturum","hash",40) //40 saat boyunca kalır.

var cerez = Cookie('hash');
if(cerez!=null || cerez!=''){
//islem yap..
}else{ //islem yapma}