Setting Cookies to Subdomains in JavaScript

We've recently faced a problem of setting a cookie from foo.mycompany.com to all subdomains in a *.mycompany.com domain.

The solution seemed pretty straightforward: just set a wildcard cookie to .mycompany.com (note that the first character is a dot). However, we had to determine the target domain (the actual value of “.mycompany.com”) automatically because our code is fired on tens of thousands of different domains.

And here came the problem: the list of Top-Level Domains.

Continue reading →