https://manabuneko.com/sw-txt-nav-guard.js

1/* Manabu Neko — navigate-only guard for Next.js static-export RSC `.txt` URLs.
2 *
3 * Soft navigations fetch `*.txt` RSC payloads (must keep working).
4 * Full document navigations to those URLs make mobile Chrome download text/plain.
5 * Intercept only request.mode === "navigate" and send users to the HTML route.
6 */
7const PASSTHROUGH = new Set(["/ads.txt", "/robots.txt"]);
8
9self.addEventListener("install", (event) => {
10  event.waitUntil(self.skipWaiting());
11});
12
13self.addEventListener("activate", (event) => {
14  event.waitUntil(self.clients.claim());
15});
16
17self.addEventListener("fetch", (event) => {
18  if (event.request.mode !== "navigate") return;
19
20  let url;
21  try {
22    url = new URL(event.request.url);
23  } catch {
24    return;
25  }
26
27  if (url.origin !== self.location.origin) return;
28  if (!url.pathname.endsWith(".txt")) return;
29  if (PASSTHROUGH.has(url.pathname)) return;
30
31  let path = url.pathname.slice(0, -".txt".length);
32  if (path.endsWith("/index")) {
33    path = path.slice(0, -"/index".length) || "/";
34  }
35
36  const nextMarker = path.indexOf("/__next.");
37  if (nextMarker !== -1) {
38    path = path.slice(0, nextMarker) || "/";
39  }
40
41  if (!path) path = "/";
42
43  const dest = `${path}${url.search}${url.hash}`;
44  event.respondWith(Response.redirect(new URL(dest, url.origin), 302));
45});