function registerValidSW()

in packages/typescript-example/src/serviceWorker.js [57:99]
33 lines of code
8 McCabe index (conditional complexity)

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 http://bit.ly/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);
        });
}