index.js

export default function App () {
    
    if ('serviceWorker' in navigator) {
        navigator.serviceWorker
            .register('firebase-messaging-sw.js')
            .then(function(registration) {
                console.log('[SW]: SCOPE: ', registration.scope);
                return registration.scope;
            })
            .catch(function(err) {
                return err;
            });
    }
    
    return <div> </div>
}