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<!DOCTYPE html>
<script>
const worker = new Worker("worker.js");
async function pageProbe() {
const result = { controlled: !!navigator.serviceWorker.controller };
try {
const response = await fetch("probe?" + Math.random());
result.status = response.status;
result.body = await response.text();
} catch (e) {
result.error = e.message;
}
return result;
}
function workerProbe() {
return new Promise(resolve => {
worker.addEventListener("message", e => resolve(e.data), { once: true });
worker.postMessage("probe");
});
}
window.addEventListener("message", async function () {
// Run the two probes sequentially so that neither can mask a failure of
// the other by keeping the service worker alive.
const page = await pageProbe();
const workerResult = await workerProbe();
parent.postMessage({ page, worker: workerResult }, "*");
});
</script>