The enable() method of the NavigationPreloadManager interface is used to enable preloading of resources managed by the service worker. It returns a promise that resolves with undefined.

The method should be called in the service worker's activate event handler, which ensures it is called before any fetch event handler can fire.

None.

A Promise that resolves with undefined.

InvalidStateError DOMException

There is no active worker associated with the registration to which this NavigationPreloadManager belongs.

The code below shows how to enable preloading, after first using ServiceWorkerRegistration.navigationPreload to test that it is supported.

addEventListener("activate", (event) => {
  event.waitUntil(
    (async () => {
      if (self.registration.navigationPreload) {
        // Enable navigation preloads!
        await self.registration.navigationPreload.enable();
      }
    })(),
  );
});