visibilitychange API, and websites are allowed to modify their own title and favicon programatically. Favicon can be part of the DOM ever since icons via ~~met

visibilitychange API, and websites are allowed to modify their own title and favicon programatically. Favicon can be part of the DOM ever since icons via ~~meta~~ link tags were introduced, because they can be more hi-res than the default favicon.ico file. I've never thought about the ability to swap it dynamically though, although I've seen some site do that before. https://developer.mozilla.org/en-US/docs/Web/API/Document/visibilitychange_event https://developer.mozilla.org/en-US/docs/Web/API/Document/vi... https://developer.mozilla.org/en-US/docs/Web/API/Document/title https://developer.mozilla.org/en-US/docs/Web/API/Document/ti... https://html.spec.whatwg.org/multipage/links.html#rel-icon https://html.spec.whatwg.org/multipage/links.html#rel-icon