isNavigationPreloadSupported

import {
  enableNavigationPreload,
  disableNavigationPreload,
  isNavigationPreloadSupported,
  NavigationRoute,
  NetworkFirst,
} from "serwist";

declare const self: ServiceWorkerGlobalScope;

self.addEventListener("message", (event) => {
  if (event.data && event.data.type === "TOGGLE_NAV_PRELOAD") {
    event.waitUntil(
      (async () => {
        if (isNavigationPreloadSupported()) {
          const state = await self.registration.navigationPreload.getState();
          if (state.enabled) {
            disableNavigationPreload();
          } else {
            enableNavigationPreload();
          }
        }
      })(),
    );
  }
});

// Swap in NetworkOnly, CacheFirst, or StaleWhileRevalidate as needed.
const navigationStrategy = new NetworkFirst({
  cacheName: "cached-navigations",
});

const navigationRoute = new NavigationRoute(navigationStrategy, {
  // Optionally, provide a allow/denylist of RegExps to determine
  // which paths will match this route.
  // allowlist: [],
  // denylist: [],
});

serwist.registerRoute(navigationRoute);