How to pass data to your service worker without relying on the GET query string:

// Main script:

const worker = navigator.serviceWorker.register
(
  'sw.js',
  {
    scope: '/',
    type: 'module',
  }
);

worker.ready.then
(
  controller =>
  {
    // You can actually send JS data.
    controller.postMessage({greeting: 'Hello world.'});
  }
);

// sw.js

navigator.serviceWorker.addEventListener
(
  'message', message =>
  {
    console.log('Message from Main script:', message);
  }
);