davidflanagan.com/javascript5

<script src="Cookie.js"></script><!-- include the cookie class -->
<script>
// Create the cookie we'll use to save state for this web page.
var cookie = new Cookie("vistordata");

// First, try to read data stored in the cookie. If the cookie doesn't 
// exist yet (or doesn't have the data we expect), query the user
if (!cookie.name || !cookie.color) {
    cookie.name = prompt("What is your name:", "");
    cookie.color = prompt("What is your favorite color:", "");
}

// Keep track of how many times this user has visited the page
if (!cookie.visits) cookie.visits = 1;
else cookie.visits++;

// Store the cookie data, which includes the updated visit count.  We set
// the cookie lifetime to 10 days.  Since we don't specify a path, this
// cookie will be accessible to all web pages in the same directory as this
// one or "below" it.  We should be sure, therefore that the cookie
// name, "visitordata" is unique among these pages.
cookie.store(10);

// Now we can use the data we obtained from the cookie (or from the
// user) to greet a user by name and in her favorite color.
document.write('<h1 style="color:' + cookie.color + '">' +
               'Welcome, ' + cookie.name + '!' + '</h1>' +
               '<p>You have visited ' + cookie.visits + ' times.' + 
               '<button onclick="window.cookie.remove();">Forget Me</button>');
</script>