The CloseWatcher API listens and responds to close requests on in-page components, such as modals, popovers, and sidebars. Shipping in Safari 27.3 (beta). Probes CloseWatcher. More: developer.mozilla.org/docs/Web/API/CloseWatcher html.spec.whatwg.org/multipage/interaction.html#cl… web-platform-dx.github.io/web-features-explorer/fe…
typeof CloseWatcher !== "undefined"typeof CloseWatcher !== "undefined"