Add ServiceWorker

app.js

@@ -202,3 +202,11 @@ window.onpopstate = function(event) {
 	return v.length > 0;
     }), true);
 }
+
+if ('serviceWorker' in navigator) {
+    navigator.serviceWorker.register('/sw.js').then(function(registration) {
+	console.log('Service worker registration succeeded:', registration);
+    }).catch(function(error) {
+	console.log('Service worker registration failed:', error);
+    });
+}

sw.js

@@ -0,0 +1,70 @@
+const cacheName = "v1";
+
+self.addEventListener("install", function(e) {
+    e.waitUntil(
+	caches.open(cacheName).then(function(cache) {
+	    return cache.addAll([
+		'/',
+		'/style.css',
+		'/app.js',
+		'/jquery-3.3.1.min.js',
+		'/favicon.ico',
+		'/fonts/Parisine-Bold.eot',
+		'/fonts/Parisine-BoldItalic.eot',
+		'/fonts/Parisine-BoldItalic.woff',
+		'/fonts/Parisine-Bold.woff',
+		'/fonts/Parisine-Italic.ttf',
+		'/fonts/Parisine-Italic.woff',
+		'/fonts/Parisine-Regular.eot',
+		'/fonts/Parisine-Regular.woff',
+		'/bootstrap.min.css',
+		'/logo.svg',
+	    ]);
+	})
+    )
+})
+
+self.addEventListener("activate", function(e) {
+    e.waitUntil(
+	caches.keys().then(function(cacheNames) {
+	    return Promise.all(cacheNames.map(function(cName) {
+		if (cName != cacheName) {
+		    return caches.delete(cName);
+		}
+	    }))
+	})
+    )
+})
+
+self.addEventListener("fetch", function(e) {
+    var url = e.request.url.split("/");
+
+    e.respondWith(
+	caches.match(e.request)
+	    .then(function(response) {
+		if (response) {
+		    // Return cached version
+		    return response;
+		}
+
+		var requestClone = e.request.clone();
+		return fetch(requestClone)
+		    .then(function(response) {
+
+			if(!response || response.type !== 'basic') {
+			    return response;
+			}
+
+			if (!(url[3] == "api" && (url[4] == "traffic" || url[4] == "schedules"))) {
+			    var responseClone = response.clone();
+			    caches.open(cacheName).then(function(cache) {
+				cache.put(e.request, responseClone);
+			    });
+			}
+
+			// Return the response
+			return response;
+		    })
+	    })
+    );
+})