ireade

self.addEventListener('install', (e) => {
    e.waitUntil(
        caches.open("precache").then((cache) => cache.add("/broken.png"))
    );
});

function isImage(fetchRequest) {
    return fetchRequest.method === "GET" && fetchRequest.destination === "image";
}

addyosmani

Route-based chunking

Many of us building single-page apps today use JavaScript module bundling tools that trend towards a monolithic "bundle.js" file including the full app and vendor code for multiple routes. This means if a user lands on any arbitrary route they need to wait for a large bundle of JS to be fetched, parsed and executed before the application is fully rendered and interactive.

This is a little backwards, especially when apps are used under real-world network (3G) and device