Service Workers & Progressive Web Apps

How should cross-origin requests be handled in a Service Worker?

self.addEventListener('fetch', event => {
  if (event.request.url.startsWith('https://api.example.com')) {
    event.respondWith(
      fetch(event.request.clone(), {
        mode: 'cors',
        credentials: 'same-origin'
      }).catch(() => {
        return caches.match(event.request);
      })
    );
  }
});

Block all cross-origin requests
Ignore cross-origin requests
Handle with appropriate CORS headers and mode
Cross-origin requests in Service Workers require: 1) Proper CORS headers from the server, 2) Appropriate fetch mode ('cors', 'no-cors', etc.), 3) Careful handling of credentials, 4) Fallback strategies for failed requests. Ensure the server provides necessary CORS headers and handle responses according to the application's security requirements.
Always serve from cache

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