This will break user experience in IE8/9 badly, somehow storing a session cookie alongside large data sets in sessionStorage will block the UI on page reload/just before unload

gistfile1.js

// Create random value for key and value purposes, ignore the globals...
test = Math.round(Math.random()+1);

// Prepare data to be written
kilo = []; 
lol = (function () {for(var i = 0; i < 100000; i++) { kilo.push({test: test}); }})();

// Write to sessionstorage
sessionStorage.setItem('lol' + test, JSON.stringify(kilo));

// Store some cookie
document.cookie = 'lol=yup writing; path=/; domain = .' + document.domain;

// The problem lies in the fact that the cookie is also written as session cookie... setting expires will fix it :D
dated = new Date;
dated.setMonth(dated.getMonth()+1);
document.cookie = 'lol=yup writing; expires=' + dated.toUTCString() + '; path=/; domain = .' + document.domain;