workboxrouting

Workbox routing, or the workbox-routing module, is a component of the Google Workbox library that provides a framework for handling fetch events in a service worker. It enables developers to declare how different network requests should be processed and cached, helping to implement offline support and performance optimizations.

The routing system works by intercepting fetch events and directing them to appropriate route handlers. Routes can be defined using URL patterns, regular expressions, or custom matcher functions, and can apply to specific HTTP methods. When a request matches a route, the associated handler determines how the request should be answered, typically by using a caching strategy from the related workbox-strategies module.

Key features include the ability to create a Router or use helper APIs such as registerRoute, as well as specialized route types like RegExpRoute and NavigationRoute. Routes are paired with strategies such as CacheFirst, NetworkFirst, NetworkOnly, CacheOnly, or StaleWhileRevalidate, which govern how responses are retrieved and cached. Plugins can be attached to routes to extend behavior, for example to enforce cacheable responses or manage cache expiration.

Typical use cases involve runtime caching for assets and API responses, enabling offline capability and faster subsequent loads. Workbox routing integrates with other Workbox modules to provide a cohesive caching strategy, including precaching for assets loaded at install time and runtime caching for dynamic requests. It is maintained as part of the Workbox library family and supports modern browsers with service workers.