Javascript communication skills for iframe subpages and parent pages in the same domain or different domains

The communication method varies depending on whether the src attribute in iframe is the same domain link or cross-domain link. The following is a good example, for more information about the communication between the iframe subpage and the parent page, see whether the src attribute in iframe is the same domain link or cross-domain link.

1. Communication between parent and child pages in the same domain

Parent page parent.html

The Code is as follows: