browser-root-domain

Get root domain in browser.

Install

npm install --save root-domain-lite
# or
yarn add root-domain-lite

Why

Some domain sufixies are like .net.cn, while some are like .cn .io. See Public Suffix List.

For now, we do not have any perfect idea to distinguish between such cases. Enumeration? Crazy!

Don't sigh, we still have two idea that would help us:

if you set document.domain to .net.cn on a page, you would get an error;

you will not succeed when setting cookie with a domain=.net.cn option.

With the former idea, we could set document.domain repeatedly until success. For example, first try document.domain = 'net.cn', then try document.domain = 'xyz.net.cn'... Done!

Wait! Should we restore document.domain? Definitely!

Try to run document.domain = origianl_domain.

Chrome, hmm, OK.

Firefox? Oops!

It seems that, once document.domain is set to a superior one in Firefox, you can never set it back. Bad news.

So we have to turn to the latter idea. Cookie is not as stricky as document.domain. Just take a look at the source code ~