React Unexpected token 'export' when implementing serviceworker

Question

I'm pretty new to react and I'm trying to implement a service worker at the moment. Actually I always get an error 'Uncaught SyntaxError: Unexpected token 'export'' in my "serviceworker.js" class.

Here's my main.tsx file.

import React from 'react';
import ReactDOM from 'react-dom';
import 'bootstrap/dist/css/bootstrap.css';
import App from './app/app';
import * as registerServiceWorker from './serviceworker/serviceworker';

ReactDOM.render(<App />, document.getElementById('root'));
registerServiceWorker.register();

And thats my "serviceworker.js" file.

 const isLocalhost = Boolean(


  window.location.hostname === 'localhost' ||
     // [::1] is the IPv6 localhost address.
     window.location.hostname === '[::1]' ||
     // 127.0.0.1/8 is considered localhost for IPv4.
     window.location.hostname.match(
       /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/
     )
   )

    export function register(config) {
    if ('serviceWorker' in navigator) {
      // The URL constructor is available in all browsers that support SW.
      // const publicUrl = new URL(process.env.PUBLIC_URL, window.location.href);
      // if (publicUrl.origin !== window.location.origin) {
      //   // Our service worker won't work if PUBLIC_URL is on a different origin
      //   // from what our page is served on. This might happen if a CDN is used to
      //
      //   return;
      // }

      window.addEventListener('load', () => {
        const swUrl = `/serviceworker/serviceworker.js`;

        if (isLocalhost) {
          // This is running on localhost. Let's check if a service worker still exists or not.
          checkValidServiceWorker(swUrl, config);

          // Add some additional logging to localhost, pointing developers to the
          // service worker/PWA documentation.
          navigator.serviceWorker.ready.then(() => {
            console.log(
              'This web app is being served cache-first by a service ' +
              'worker. To learn more,  '
            );
          });
        } else {
          // Is not localhost. Just register service worker
          registerValidSW(swUrl, config);
        }
      });
    }
  }

  function registerValidSW(swUrl, config) {
    navigator.serviceWorker
      .register(swUrl)
      .then(registration => {
        registration.onupdatefound = () => {
          const installingWorker = registration.installing;
          if (installingWorker == null) {
            return;
          }
          installingWorker.onstatechange = () => {
            if (installingWorker.state === 'installed') {
              if (navigator.serviceWorker.controller) {
                // At this point, the updated precached content has been fetched,
                // but the previous service worker will still serve the older
                // content until all client tabs are closed.
                console.log(
                  'New content is available and will be used when all ' +
                  'tabs for this page are closed. See  /CRA-PWA.'
                );

                // Execute callback
                if (config && config.onUpdate) {
                  config.onUpdate(registration);
                }
              } else {
                // At this point, everything has been precached.
                // It's the perfect time to display a
                // "Content is cached for offline use." message.
                console.log('Content is cached for offline use.');

                // Execute callback
                if (config && config.onSuccess) {
                  config.onSuccess(registration);
                }
              }
            }
          };
        };
      })
      .catch(error => {
        console.error('Error during service worker registration:', error);
      });
  }

  function checkValidServiceWorker(swUrl, config) {
    // 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 contentType = response.headers.get('content-type');
        if (
          response.status === 404 ||
          (contentType === null)
        ) {
          // No service worker found. Probably a different app. Reload the page.
          navigator.serviceWorker.ready.then(registration => {
            registration.unregister().then(() => {
              window.location.reload();
            });
          });
        } else {
          // Service worker found. Proceed as normal.
          registerValidSW(swUrl, config);
        }
      })
      .catch(() => {
        console.log(
          'No internet connection found. App is running in offline mode.'
        );
      });
  }

   export function unregister() {
    if ('serviceWorker' in navigator) {
      navigator.serviceWorker.ready.then(registration => {
        registration.unregister();
      });
    }
  }

Any idea what I did wrong here? I already added Babel as suggested in this thread react export Unexpected token but the error didn't disappear. I already tried to export it via modules.export, but no sucess either.

Thanks in advance

EDIT: Thats what my ".babelrc" looks like:

    {
  "presets": ["@babel/preset-react"],
  "plugins": [
    "babel-plugin-transform-export-extensions",
    "transform-es2015-modules-commonjs"
  ]
}

Answer 1

Thats what my ".babelrc" looks like:

    {
  "presets": ["@babel/preset-react"],
  "plugins": [
    "babel-plugin-transform-export-extensions",
    "transform-es2015-modules-commonjs"
  ]
}

Answer 2

This problem occurs because you are trying to use the same file as the service worker you are registering it with. Because of this, the browser cannot figure out which service worker features you need. Use for example this content for service-worker.js in your public folder:

self.addEventListener('push', (event) => {
  const data = event.data.json();
  console.log('New notification', data);
  event.waitUntil(
  self.registration.showNotification(data.title, {
    body: data.description,
    icon: data.icon,
  })
 );
});