Javascript document.cookie always returns empty string
HttpOnly cookies cannot be accessed from Javascript and session cookies are usually set as HttpOnly cookies. See also this StackOverflow question: How to read a secure cookie using JavaScript
So... check whether the cookie you want to read has the 'HttpOnly' flag set... If so, you know the culprit. It's not a bug, it's a feature!
You can't set cookies by the look of things if its not running in a web server.
file:///C:/Users/me/Desktop/demo/demo.html
however:
http://localhost/demo/demo.html
works.
This worked for me when ran from localhost, running chrome 28.0.1472.0 canary:
<!DOCTYPE html>
<html>
<head>
<title>localhost cookie</title>
</head>
<body>
<script type="text/javascript">
console.log(document.cookie);
var myCookie = "mycookie=hellocookie";
document.cookie = myCookie;
</script>
</body>
</html>
Run it in a server, visit the page and look at your cookie store, refresh the page and look at your console.
It did not set a cookie when opened as a file but worked every time when opened from the server.