wip(js): add head.html and assets/js

assets/js/pwa/sw.js

@@ -0,0 +1,92 @@
+importScripts('./assets/js/data/swconf.js');
+
+const purge = swconf.purge;
+const interceptor = swconf.interceptor;
+
+function verifyUrl(url) {
+  const requestUrl = new URL(url);
+  const requestPath = requestUrl.pathname;
+
+  if (!requestUrl.protocol.startsWith('http')) {
+    return false;
+  }
+
+  for (const prefix of interceptor.urlPrefixes) {
+    if (requestUrl.href.startsWith(prefix)) {
+      return false;
+    }
+  }
+
+  for (const path of interceptor.paths) {
+    if (requestPath.startsWith(path)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+self.addEventListener('install', (event) => {
+  if (purge) {
+    return;
+  }
+
+  event.waitUntil(
+    caches.open(swconf.cacheName).then((cache) => {
+      return cache.addAll(swconf.resources);
+    })
+  );
+});
+
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys().then((keyList) => {
+      return Promise.all(
+        keyList.map((key) => {
+          if (purge) {
+            return caches.delete(key);
+          } else {
+            if (key !== swconf.cacheName) {
+              return caches.delete(key);
+            }
+          }
+        })
+      );
+    })
+  );
+});
+
+self.addEventListener('message', (event) => {
+  if (event.data === 'SKIP_WAITING') {
+    self.skipWaiting();
+  }
+});
+
+self.addEventListener('fetch', (event) => {
+  if (event.request.headers.has('range')) {
+    return;
+  }
+
+  event.respondWith(
+    caches.match(event.request).then((response) => {
+      if (response) {
+        return response;
+      }
+
+      return fetch(event.request).then((response) => {
+        const url = event.request.url;
+
+        if (purge || event.request.method !== 'GET' || !verifyUrl(url)) {
+          return response;
+        }
+
+        // See: <https://developers.google.com/web/fundamentals/primers/service-workers#cache_and_return_requests>
+        let responseToCache = response.clone();
+
+        caches.open(swconf.cacheName).then((cache) => {
+          cache.put(event.request, responseToCache);
+        });
+        return response;
+      });
+    })
+  );
+});