About document.domain to solve cross-domain problems

document.domain

The domain property returns the domain name of the server that downloaded the current document.

have to be aware of is:

First of all, it is possible to use document.domain to specify the domain, but there are limitations, that is, only the first-level domain name can be consistent.

Also, both pages must be specified

Reference blog:

http://www.cnblogs.com/jkisjk/archive/2013/05/30/change_document_domain.html

https://www.sojson.com/blog/179.html