Part 3 explores Sapper, a tool that builds on Svelte to add more features. We’ll build our first Sapper application, which will recreate the shopping app we developed earlier in the book, and take a closer look at Sapper’s unique features, such as page routes, page layouts, preloading, prefetching, and code splitting. We’ll also cover server routes, which enable API service implementation in the same project as the client side of a web app. Sapper apps can be “exported” to generate static sites, which can be desirable when you want to generate the HTML for every page at build time. This part will cover that topic and look at an example app that builds on it, along with service worker caching strategies and events. Finally, we’ll look at techniques to verify the offline behavior of a Sapper app.