Guardar y leer cookies con javascript

Para guardar y posteriormente leer cookies guardadas en el equipo del cliente haremos lo siguiente:

function getCookie(c_name){
ovar c_value = document.cookie;
ovar c_start = c_value.indexOf(" " + c_name + "=");
oif (c_start == -1){
oc_start = c_value.indexOf(c_name + "=");
o}
oif (c_start == -1){
oc_value = null;
o}else{
oc_start = c_value.indexOf("=", c_start) + 1;
ovar c_end = c_value.indexOf(";", c_start);
oif (c_end == -1){
oc_end = c_value.length;
o}
oc_value = unescape(c_value.substring(c_start,c_end));
o}
oreturn c_value;
}
function setCookie(c_name,value,exdays){
ovar exdate = new Date();
oexdate.setDate(exdate.getDate() + exdays);
ovar c_value = escape(value) + ((exdays==null) ? "" : "; expires=" + exdate.toUTCString());
odocument.cookie = c_name + "=" + c_value;
}
function checkCookie(){
ovar popupNL = getCookie("popupENCvb");
oif (popupNL != "true"){
oxarxaON();
o//setCookie("popupENCvb", "true", 30);
o}
}

Otro ejemplo:

var expDays = 15; // nombre de jours le cookie va rester
var nxtime = 150; // nombre de fois d'affichage de la popup

function GetCookie (name) {  
var arg = name + "=";  
var alen = arg.length;  
var clen = document.cookie.length;  
var i = 0;  
while (i < clen) {    
var j = i + alen;    
if (document.cookie.substring(i, j) == arg)      
return getCookieVal (j);    
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;  
var expires = (argc > 2) ? argv[2] : null;  
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();
}
var exp = new Date(); 
exp.setTime(exp.getTime() + (expDays*24*60*60*1000));
function amt(){
var count = GetCookie('count')
if(count == null) {
SetCookie('count','1')
return 1
}
else {
var newcount = parseInt(count) + 1;
DeleteCookie('count')
SetCookie('count',newcount,exp)
return count
   }
}
function getCookieVal(offset) {
var endstr = document.cookie.indexOf (";", offset);
if (endstr == -1)
endstr = document.cookie.length;
return unescape(document.cookie.substring(offset, endstr));
}

function checkCount() {
var count = GetCookie('count');
if (count == null || count<nxtime) {
count++;
SetCookie('count', count, exp);
document.getElementById('popindiv').style.display='block';
document.getElementById('bck_gd').style.display='block'
}
}