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function synthesizeImage(suffix) {
// Serve image-20px for the first page, and image-40px for the second page.
return clients
.matchAll()
.then(clients => {
var url = "image-20px.png";
clients.forEach(client => {
if (client.url.indexOf("?new") > 0) {
url = "image-40px.png";
}
client.postMessage({ suffix, url });
});
return fetch(url);
})
.then(response => {
return response.arrayBuffer();
})
.then(ab => {
var headers;
if (suffix == "") {
headers = {
"Content-Type": "image/png",
Date: "Tue, 1 Jan 1990 01:02:03 GMT",
"Cache-Control": "max-age=1",
};
} else {
headers = {
"Content-Type": "image/png",
"Cache-Control": "no-cache",
};
}
return new Response(ab, {
status: 200,
headers,
});
});
}
self.addEventListener("fetch", function (event) {
if (event.request.url.includes("image.png")) {
event.respondWith(synthesizeImage(""));
} else if (event.request.url.includes("image2.png")) {
event.respondWith(synthesizeImage("2"));
}
});