service worker, attempt 1

index.html

@@ -40,6 +40,7 @@
                 <a id="showAllWords">show all words</a> <a id="randomWord">random word</a> <a href="#">resources</a>
             </div>
             <noscript>turn on js doofus</noscript>
+            <span id="update">update available! close all open hisho tabs and reopen hisho to update.</span>
         </header>
         <main>
 

main.css

@@ -160,6 +160,10 @@ header.fullscreen #search {
     max-width: 500px;
 }
 
+header #update {
+    display: none;
+}
+
 .header-animation {
     animation: clearly-cheating 1s ease-in-out;
 }

main.js

@@ -476,6 +476,53 @@ function goHome(state = true) {
     if (state == true) history.pushState(null, "", url);
 }
 
+async function registerSW() {
+    if ('serviceWorker' in navigator) {
+        navigator.serviceWorker.register('./sw.js').then(registration => {
+            registration.onupdatefound = () => {
+                const installingWorker = registration.installing;
+                if (installingWorker == null) {
+                    return;
+                }
+                installingWorker.onstatechange = () => {
+                    if (installingWorker.state === 'installed') {
+                        if (navigator.serviceWorker.controller) {
+                            // At this point, the updated precached content has been fetched,
+                            // but the previous service worker will still serve the older
+                            // content until all client tabs are closed.
+                            header.querySelector("#update").style.display = "block";
+
+                            // Execute callback
+                            if (config && config.onUpdate) {
+                                config.onUpdate(registration);
+                            }
+                        } else {
+                            // At this point, everything has been precached.
+                            // It's the perfect time to display a
+                            // "Content is cached for offline use." message.
+                            console.log('Content is cached for offline use.');
+
+                            // Execute callback
+                            if (config && config.onSuccess) {
+                                config.onSuccess(registration);
+                            }
+                        }
+                    }
+                };
+            };
+        }).catch(error => {
+            console.error('Error during service worker registration:', error);
+        });
+    }
+}
+
+function removeSW() {
+    navigator.serviceWorker.getRegistrations().then(function(registrations) {
+        for(let registration of registrations) {
+         registration.unregister()
+    }}); //dev use only!! or whatever... i just copypasted this from SO
+}
+
 window.onload = () => {
     header = document.querySelector("header");
     main = document.querySelector("main");
@@ -513,7 +560,8 @@ window.onload = () => {
             doSearch(false);
         }
     });
-    //also check if ?s is there . for hecks sake (todo)
+    registerSW();
+    //also check if ?s is there . for hecks sake (todo) (TODO!!!!!!)
 }
 
 const sortObject = obj => Object.keys(obj).sort().reduce((res, key) => (res[key] = obj[key], res), {})

sw.js

@@ -0,0 +1,91 @@
+const currentVersion = 'v1';
+
+const addResourcesToCache = async (resources) => {
+    const cache = await caches.open(currentVersion);
+    await cache.addAll(resources);
+};
+
+const putInCache = async (request, response) => {
+    const cache = await caches.open(currentVersion);
+    await cache.put(request, response);
+};
+
+const cacheFirst = async ({ request, preloadResponsePromise }) => {
+    // First try to get the resource from the cache
+    const responseFromCache = await caches.match(request);
+    if (responseFromCache) {
+        return responseFromCache;
+    }
+
+    // Next try to use the preloaded response, if it's there
+    const preloadResponse = await preloadResponsePromise;
+    if (preloadResponse) {
+        console.info('using preload response', preloadResponse);
+        putInCache(request, preloadResponse.clone());
+        return preloadResponse;
+    }
+
+    // Next try to get the resource from the network
+    try {
+        const responseFromNetwork = await fetch(request);
+        // response may be used only once
+        // we need to save clone to put one copy in cache
+        // and serve second one
+        putInCache(request, responseFromNetwork.clone());
+        return responseFromNetwork;
+    } catch (error) {
+        return new Response('Network error happened', {
+            status: 408,
+            headers: { 'Content-Type': 'text/plain' },
+        });
+    }
+};
+
+const deleteCache = async key => {
+    await caches.delete(key)
+}
+
+const deleteOldCaches = async () => {
+    const cacheKeepList = [currentVersion];
+    const keyList = await caches.keys()
+    const cachesToDelete = keyList.filter(key => !cacheKeepList.includes(key))
+    await Promise.all(cachesToDelete.map(deleteCache));
+}
+
+self.addEventListener('activate', (event) => {
+    event.waitUntil(deleteOldCaches());
+});
+
+const enableNavigationPreload = async () => {
+    if (self.registration.navigationPreload) {
+        // Enable navigation preloads!
+        await self.registration.navigationPreload.enable();
+    }
+};
+
+self.addEventListener('activate', (event) => {
+    event.waitUntil(enableNavigationPreload());
+});
+
+self.addEventListener('install', (event) => {
+    event.waitUntil(
+        addResourcesToCache([
+            './heonian-resources/wordlist.json',
+            './heonian-ime/ime.js',
+            './font.otf',
+            './index.html',
+            './main.css',
+            './main.js',
+            './manifest.json'
+        ])
+    );
+});
+
+self.addEventListener('fetch', (event) => {
+    event.respondWith(
+        cacheFirst({
+            request: event.request,
+            preloadResponsePromise: event.preloadResponse
+        })
+    );
+});