I understand that client-side first party cookies refer to cookies created on the page being browsed using document.cookie. However, I’m having trouble understanding client-side third party cookies. Is this conceptually possible but not practically, as when I try to specify a different domain using the domain parameter with document.cookie, the browser doesn’t save the cookie? Is my understanding correct?
>Solution :
Yes.
Third-party cookies can only be set by set-cookie HTTP response headers (or upon visits to the other site at which time they would be first-party cookies).
Client-side JS has no direct access to them, for reading or writing, via document.cookie or otherwise.