self.addEventListener("fetch", (event) => {
    if (event.request.url.indexOf("test1") !== -1) {
        event.respondWith(new Response(null, { status: 200, statusText: "Hello from service worker", headers: [["Hello", "World"]] }));
        return;
    }
    if (event.request.url.indexOf("test2") !== -1) {
        event.respondWith(new Response(null, { status: 500, statusText: "Error from service worker" }));
        return;
    }
    if (event.request.url.indexOf("test3") !== -1) {
        event.respondWith(Response.error());
        return;
    }
    if (event.request.url.indexOf("test4") !== -1)
        return;

    if (event.request.url.indexOf("test5") !== -1) {
        event.preventDefault();
        return;
    }

    if (event.request.mode !== "navigate") {
        event.respondWith(Response.error());
        return;
    }
    event.respondWith(fetch(event.request.url));
});