asd

sw.js

@@ -0,0 +1,75 @@
+/*
+ * Offline copy of the public calculator (field staff often have weak signal).
+ *  - The calculator page: network first (fresh parameters), stored copy when
+ *    offline or slow. Responses marked no-store (admin views) are never kept.
+ *  - Versioned assets (assets/...?v=): stored copy first.
+ *  - calc.php, admin/ and everything else: network only, never stored.
+ */
+'use strict';
+var CACHE = 'serubi-v1';
+var PAGE_TIMEOUT_MS = 4000;
+var SCOPE = self.registration.scope;          // e.g. https://host/ or http://localhost/calcserubi-prod/
+var PAGE_KEY = SCOPE;                         // one stored copy of the calculator, whatever the query string
+
+self.addEventListener('install', function () { self.skipWaiting(); });
+
+self.addEventListener('activate', function (event) {
+  event.waitUntil(caches.keys().then(function (keys) {
+    return Promise.all(keys.filter(function (k) { return k !== CACHE; }).map(function (k) { return caches.delete(k); }));
+  }).then(function () { return self.clients.claim(); }));
+});
+
+function isCalculatorPage(url) {
+  var rel = url.href.slice(SCOPE.length).split('?')[0];
+  return rel === '' || rel === 'index.php';
+}
+
+function storable(res) {
+  return res && res.ok && res.type === 'basic' && !/no-store/i.test(res.headers.get('Cache-Control') || '');
+}
+
+function pageNetworkFirst(request) {
+  return caches.open(CACHE).then(function (cache) {
+    var network = fetch(request).then(function (res) {
+      if (storable(res)) cache.put(PAGE_KEY, res.clone());
+      return res;
+    });
+    network.catch(function () { /* handled below */ });
+    var timeout = new Promise(function (resolve) { setTimeout(resolve, PAGE_TIMEOUT_MS); });
+    // slow network: answer from the stored copy after the timeout, if there is one
+    return Promise.race([network, timeout.then(function () { return cache.match(PAGE_KEY).then(function (c) { return c || network; }); })])
+      .catch(function () { return cache.match(PAGE_KEY).then(function (c) { if (c) return c; throw new Error('offline'); }); });
+  });
+}
+
+function assetCacheFirst(request) {
+  return caches.open(CACHE).then(function (cache) {
+    return cache.match(request).then(function (hit) {
+      if (hit) return hit;
+      return fetch(request).then(function (res) {
+        if (storable(res)) {
+          // keep only the newest version (?v=) of each asset
+          var path = new URL(request.url).pathname;
+          cache.keys().then(function (keys) {
+            keys.forEach(function (k) { if (new URL(k.url).pathname === path && k.url !== request.url) cache.delete(k); });
+          });
+          cache.put(request, res.clone());
+        }
+        return res;
+      });
+    });
+  });
+}
+
+self.addEventListener('fetch', function (event) {
+  var req = event.request;
+  if (req.method !== 'GET') return;
+  var url = new URL(req.url);
+  if (url.origin !== self.location.origin || req.url.indexOf(SCOPE) !== 0) return;
+  if (req.mode === 'navigate' && isCalculatorPage(url)) {
+    event.respondWith(pageNetworkFirst(req));
+  } else if (url.pathname.indexOf('/assets/') !== -1) {
+    event.respondWith(assetCacheFirst(req));
+  }
+  // anything else (calc.php, admin/, ...) goes straight to the network
+});