| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <link id="prefetch" rel="prefetch" href="pass.png"> | |
| </head> | |
| <body> | |
| <script> | |
| const bc = new BroadcastChannel(new URLSearchParams(location.search).get("uid")); | |
| document.getElementById("prefetch").addEventListener("error", e => bc.postMessage(false)); | |
| const observer = new PerformanceObserver(entries => { | |
| const found = entries.getEntriesByName(new URL("pass.png", location.href).href); | |
| if (found.length) | |
| bc.postMessage(found[0].encodedBodySize > 0); | |
| }); | |
| observer.observe({entryTypes: ["resource"]}); | |
| </script> | |
| </body> | |
| </html> |