export default function register()

in src/registerServiceWorker.js [22:55]

• 26 lines of code
• 8 McCabe index (conditional complexity)

export default function register() {
  if (
    process.env.NODE_ENV === "production" &&
    "serviceWorker" in navigator &&
    process.env.PUBLIC_URL &&
    navigator.serviceWorker
  ) {
    // The URL constructor is available in all browsers that support SW.
    const publicUrl = new URL(
      process.env.PUBLIC_URL,
      window.location.toString()
    );
    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
      // serve assets; see https://github.com/facebookincubator/create-react-app/issues/2374
      return;
    }

    window.addEventListener("load", () => {
      if (process.env.PUBLIC_URL) {
        const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;

        if (!isLocalhost) {
          // Is not local host. Just register service worker
          registerValidSW(swUrl);
        } else {
          // This is running on localhost. Lets check if a service worker still exists or not.
          checkValidServiceWorker(swUrl);
        }
      }
    });
  }
}