| <!DOCTYPE html> | |
| <script> | |
| const channel = new MessageChannel(); | |
| window.parent.postMessage({ state: "port1", data: channel.port1 }, '*', [channel.port1]); | |
| window.onmessage = () => window.parent.postMessage({ state: "port2", data: channel.port2 }, '*', [channel.port2]); | |
| </script> |