What does the isDomain property of nsICookie mean?

Question

Can anybody give me a further explanation about the isDomain property of the nsICookie interface?

Answer 1

If .isDomain is true, the cookie is to be used for the whole domain (host + all subdomains), otherwise it is only to be used for a specific host.

When setting the cookie and specifying a domain= value with a leading ., the cookie becomes a domain cookie. See the document.cookie documentation.

E.g.

• domain=.example.org will be a domain cookie (.isDomain == true) and will be used for example.org and all sub-domains, such as www.example.org.
• domain=example.org will not be a domain cookie (.isDomain == false) and will only be used for example.org, but not for subdomains.
• domain=www.example.org will not be a domain cookie (.isDomain == false) and will only be used for www.example.org, but not for subdomains.

It is implemented simply as:

inline bool IsDomain() const { return /* const char* */ *mHost == '.'; }

meaning: Return true if the first char of the string is a ., else return false.