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MessagePort.postMessage() may throw
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| <!-- | |
| Proof that cross-realm `MessagePort.postMessage()` can throw. | |
| --> | |
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>Foo</title> | |
| </head> | |
| <body> | |
| <iframe | |
| id="myIframe" | |
| srcdoc=" | |
| <!DOCTYPE html> | |
| <html lang='en'> | |
| <head> | |
| </head> | |
| <body> | |
| <script type='module'> | |
| console.log('iframe'); | |
| let port; | |
| window.addEventListener('message', message => { | |
| port = message.ports[0]; | |
| // MessageEvents are not cloneable, so this will throw. | |
| port.onmessage = message => port.postMessage({ echo: message }); | |
| }); | |
| </script> | |
| </body> | |
| </html> | |
| " | |
| ></iframe> | |
| <script type="module"> | |
| const delay = (ms = 100) => new Promise(resolve => setTimeout(resolve, ms)); | |
| const { port1, port2 } = new MessageChannel(); | |
| port1.onmessage = message => console.log('received message', message); | |
| const iframe = document.getElementById('myIframe'); | |
| await delay(200); | |
| iframe.contentWindow.postMessage(null, '*', [port2]); | |
| await delay(100); | |
| console.log('sending to iframe'); | |
| port1.postMessage(null); | |
| console.log('sent'); | |
| </script> | |
| </body> | |
| </html> |
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