I need it persists after I close and open the navigator again...
Ok, that's what I do:
function SetCookie (name, value, per, exp) {
cstr = name + "=" + escape(value) + ";"
if(per){
addtime=(exp*24*60*60*1000)
expdate = new Date()
expdate.setTime(expdate.getTime() + addtime)...