Broadcast Channel API - Web APIs | MDN

The Broadcast Channel API allows basic communication between browsing contexts (that is, windows, tabs, frames, or iframes) and workers on the same origin. By creating a BroadcastChannel object, you can receive any messages that are posted to it. You don't have to maintain a reference to the frames or workers you wish to communicate with: they can "subscribe" to a particular channel by constructing their own BroadcastChannel with the same name, and have bi-directional communication between all of them.