Execute code for X visits

This JavaScript will let you execute code a certain number of times. For example, you might want to only show a pop up to visitors on their first 3 visits.

// the number of times the code should execute for a given visitor,
// the number of days the evaluation limit should last,
// and name of the cookie we use as the counter
var limit = 3,
    days = 180;
    cookieName = 'counterCookie';

// function to fetch cookie values
var getCookie = function(name) {
    var match = document.cookie.match(name+'=([^;]*)');

    return match ? match[1] : undefined;
};

// function to create cookies
var setCookie = function(c_name,value,exdays,c_domain) {
    c_domain = (typeof c_domain === "undefined") ? "" : "domain=" + c_domain + ";";
    var exdate=new Date();
    exdate.setDate(exdate.getDate() + exdays);
    var c_value=escape(value) + ((exdays==null) ? "" : "; expires="+exdate.toUTCString());
    document.cookie=c_name + "=" + c_value + ";" + c_domain + "path=/";
}

// logic that counts and limits number of times code can evaluate for given visitor
if (!getCookie(cookieName)) {
    setCookie(cookieName, 1, days, window.location.hostname);
} else {
    var numberPops = parseInt(getCookie(cookieName)) + 1;
    setCookie(cookieName, numberPops, days, window.location.hostname);
}

if (getCookie(cookieName) <= limit) {
    // Function to be evaluated here
}

This code was shamelessly stolen from getbutterfly.com – check them out for lots more Javascript tutorials!