FlakeTest/client/index.js

import { Elm } from "./elm/Main.elm";

Elm.Main.init(
  { node: document.getElementById("root") }
);

if ('serviceWorker' in navigator) {
  window.addEventListener('load', function() {
    navigator.serviceWorker.register(new URL('./sw.js', import.meta.url)).then(function(registration) {
      // Registration was successful
      console.log('ServiceWorker registration successful with scope: ', registration.scope);
    }, function(err) {
      // registration failed :(
      console.log('ServiceWorker registration failed: ', err);
    });
  });
}