| <script> | |
| const channelName = new URL(location).searchParams.get("channelname"), | |
| channel = new BroadcastChannel(channelName); | |
| channel.postMessage({ haveOpener: window.opener !== null, | |
| referrer: document.referrer }); | |
| // Because messages are not delivered synchronously and because closing a | |
| // browsing context prompts the eventual clearing of all task sources, this | |
| // document should not be closed until the opener document has confirmed | |
| // receipt. | |
| channel.onmessage = () => window.close(); | |
| </script> |