---
url: /api/symbols/workbox-swkit/core/routehandlercallback.md
---

# RouteHandlerCallback

Interface @vite-pwa/workbox-swkit/core

The "handler" callback is invoked whenever a `Router` matches a URL/Request
to a `Route` via its `RouteMatchCallback`. This handler callback should
return a `Promise` that resolves with a `Response`.

If a non-empty array or object is returned by the `RouteMatchCallback` it
will be passed in as this handler's `options.params` argument.