Sapper

Sapper (https://sapper.svelte.dev/) is a full-featured application framework for building multi-page Progressive Web Apps (PWAs). Sapper is based on Svelte 3, which it uses to allow developers to build pages and components, and it is maintained as a sub-project of Svelte itself. Among developers working with Svelte, Sapper has a modest but growing fanbase. (We saw a brief mention of multi-page applications and PWAs in Chapter 1, Meet Svelte, and we compared them with Single-Page Applications (SPAs), such as the one we were about to start building, throughout this book.)

With Sapper, developers can write components using Svelte, just like we've seen in Chapter 3, Building Reactive Svelte Components, and Chapter 4, Putting your App Together. Sapper then automatically builds multi-page PWAs, enabling features such as Server-Side Rendering (SSR), routing (using a SEO-friendly router based on the HTML5 History API, which means it's better indexed by search engines),...