You can use these functions to help you create, read, and delete cookies
function createCookie(name,value,days) {
if (days) {
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
var expires = "; expires="+date.toGMTString();
}
else var expires = "";
document.cookie = name+"="+value+expires+"; path=/";
}
function readCookie(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function eraseCookie(name) {
createCookie(name, "", -1);
}
In your case just use it in more or less this way:
var x = readCookie('visualizou_popup')
if (x) {
// achou o cookie não mostra pop up
} else {
// mostra popup e cria cookie
createCookie('visualizou_popup', 'true', 1);
}