function checkValidServiceWorker()

in src/registerServiceWorker.js [90:118]

• 25 lines of code
• 6 McCabe index (conditional complexity)

function checkValidServiceWorker(swUrl) {
  // Check if the service worker can be found. If it can't reload the page.
  fetch(swUrl)
    .then((response) => {
      // Ensure service worker exists, and that we really are getting a JS file.
      const headers = response.headers || {};
      const contentType = headers.get("content-type");
      if (
        response.status === 404 ||
        (contentType && contentType.indexOf("javascript") === -1)
      ) {
        // No service worker found. Probably a different app. Reload the page.
        navigator.serviceWorker &&
          navigator.serviceWorker.ready.then((registration) => {
            registration.unregister().then(() => {
              window.location.reload();
            });
          });
      } else {
        // Service worker found. Proceed as normal.
        registerValidSW(swUrl);
      }
    })
    .catch(() => {
      console.log(
        "No internet connection found. App is running in offline mode."
      );
    });
}