Merge pull request #104 from cse110-fa22-group29/add-sw-caching

Add service worker caching towards local first functionality

source/ReviewDetails.html

@@ -7,7 +7,7 @@
 		<title>Food Journal</title>
 
 		<!--Add Favicon-->
-		<link rel="icon" type="image/x-icon" href="./assets/images/icons/favicon.ico">
+		<link rel="icon" type="image/x-icon" href="./assets/images/favicon.ico">
 
 		<!-- Recipe Card Custom Element -->
 		<script src="assets/scripts/ReviewCard.js" type="module"></script>

source/assets/scripts/ReviewDetails.js

@@ -99,7 +99,7 @@ function setupUpdate(){
 			while (tagContainer.firstChild) {
 				tagContainer.removeChild(tagContainer.firstChild);
 			}
-			let tagSetVal = currReview["tags"][i].toLowerCase()
+			let tagSetVal = currReview["tags"][i].toLowerCase();
 			for (let i = 0; i < currReview["tags"].length; i++) {
 				tagSet.add(tagSetVal);
 				let newTag = document.createElement("label");

source/assets/scripts/main.js

@@ -40,3 +40,14 @@ function initFormHandler() {
 		window.location.assign("./CreatePage.html");
 	});
 }
+
+const registerServiceWorker = async () => {
+	if ("serviceWorker" in navigator) {
+		try {
+			const registration = await navigator.serviceWorker.register("./sw.js", {scope: "./"});
+		} catch (error) {
+			console.error(`Registration failed with ${error}`);
+		}
+	}
+};
+registerServiceWorker();

source/sw.js

@@ -0,0 +1,62 @@
+const CACHE_NAME = "food-journal-v1";
+const ASSETS = [
+	"index.html",
+	"ReviewDetails.html",
+	"CreatePage.html",
+	"static/CoveredByYourGrace-Regular.ttf",
+	"static/CreatePage.css",
+	"static/Form.css",
+	"static/homepage.css",
+	"static/ReviewDetails.css",
+	"assets/images/0-star.svg",
+	"assets/images/1-star.svg",
+	"assets/images/2-star.svg",
+	"assets/images/3-star.svg",
+	"assets/images/4-star.svg",
+	"assets/images/5-star.svg",
+	"assets/images/default_plate.png",
+	"assets/images/delete_icon_for_interface.png",
+	"assets/images/edit_button_for_interface.png",
+	"assets/images/Grouppink.png",
+	"assets/images/home_button_for_interface.png",
+	"assets/images/favicon.ico",
+	"assets/images/Logo.png",
+	"assets/scripts/CreatePage.js",
+	"assets/scripts/localStorage.js",
+	"assets/scripts/main.js",
+	"assets/scripts/ReviewCard.js",
+	"assets/scripts/ReviewDetails.js"
+];
+
+/**
+ * Adds the install listener where the app assets are added to the cache
+ */
+self.addEventListener("install", async () => {
+	// open the cace
+	const cache = await caches.open(CACHE_NAME);
+	// add all elements in ASSETS to the cache, these are all the files requried for the app to run
+	await cache.addAll(ASSETS);
+});
+
+/**
+ * Adds an event listener on fetch events to serve cached resources while offline
+ * Uses a network first structure to prioritize fetching from network in case of app updates.
+ * If there are important updates, we want the user to get those if possible.
+ */
+self.addEventListener("fetch", (event) => {
+	// add a response to the fetch event
+	event.respondWith(caches.open(CACHE_NAME).then((cache) => {
+		// try to return a network fetch response
+		return fetch(event.request).then((fetchedResponse) => {
+			// if there is a response, add it to the cache
+			cache.put(event.request, fetchedResponse.clone());
+			// return the network response
+			return fetchedResponse;
+		}).catch(() => {
+			// If there is not a network response, return the cached response
+			// The ignoreVary option is used here to fix an issue where the service worker 
+			// would not serve certain requests unless the page was refreshed at least once
+			return cache.match(event.request, {ignoreVary: true}); 
+		});
+	}));
+});

specs/adrs/120122-serviceworker-netfirst.md

@@ -0,0 +1,19 @@
+# Use a network first cache second for service worker architecture 
+
+- Status: in consideration
+- Deciders: Arthur Lu, Kara Hoagland, Rhea Bhutada, George Dubinin
+- Date: 12 / 01 / 22
+
+## Decision Drivers
+
+- Need to balance the need for user ease of use and local first priority
+- Users should expect to update their app easily when they have network, but may not be expected to know how to perform a hard refresh
+- Local first priority means we should avoid unnecessary network activity when possible
+
+## Considered Options
+- Network first cache second
+- Cache first network second
+
+## Decision Outcome
+
+Chosen Option: Network first for automatic app updating.