https://planner.fahrrad-hotels.com/map-sw.js

1// Service Worker for caching map tiles, fonts, and sprites from the PMTiles server.
2// Cache-first strategy: serve from cache if available, otherwise fetch and cache.
3// This makes repeat visits near-instant since ~2-10MB of tile data is served locally.
4
5const CACHE_NAME = "map-tiles-v1";
6const TILE_HOST = "map.planner.fahrrad-hotels.com";
7
8self.addEventListener("install", () => {
9  self.skipWaiting();
10});
11
12self.addEventListener("activate", (event) => {
13  // Clean up old cache versions
14  event.waitUntil(
15    caches
16      .keys()
17      .then((keys) =>
18        Promise.all(
19          keys
20            .filter((key) => key.startsWith("map-tiles-") && key !== CACHE_NAME)
21            .map((key) => caches.delete(key))
22        )
23      )
24      .then(() => self.clients.claim())
25  );
26});
27
28self.addEventListener("fetch", (event) => {
29  const url = new URL(event.request.url);
30  if (url.hostname !== TILE_HOST) return;
31
32  event.respondWith(handleMapRequest(event.request));
33});
34
35async function handleMapRequest(request) {
36  const cache = await caches.open(CACHE_NAME);
37
38  // PMTiles uses Range requests for individual tile fetches.
39  // The Cache API matches on URL only by default, so we encode
40  // the Range header into the cache key to distinguish them.
41  const range = request.headers.get("Range");
42  const cacheKey = range
43    ? new Request(
44        request.url +
45          (request.url.includes("?") ? "&" : "?") +
46          "_r=" +
47          encodeURIComponent(range)
48      )
49    : request;
50
51  const cached = await cache.match(cacheKey);
52  if (cached) return cached;
53
54  try {
55    const response = await fetch(request);
56    // Cache successful responses (200 OK and 206 Partial Content for range requests)
57    if (response.ok || response.status === 206) {
58      cache.put(cacheKey, response.clone());
59    }
60    return response;
61  } catch (err) {
62    // Network failure — return cached version if we somehow have it, otherwise rethrow
63    const fallback = await cache.match(cacheKey);
64    if (fallback) return fallback;
65    throw err;
66  }
67}