self.addEventListener('install', function (event) {

    event.waitUntil(

        caches.open(staticCacheName).then(function (cache) {

            return cache.addAll([

                '/skeleton',

                'js/main.js',

                'css/main.css',

                'imgs/icon.png',

                'https://fonts.gstatic.com/s/roboto/v15/2UX7WLTfW3W8TclTUvlFyQ.woff',

                'https://fonts.gstatic.com/s/roboto/v15/d-6IYplOFocCacKzxwXSOD8E0i7KZn-EPnyo3HZu7kw.woff'

            ]);

        })

    );

});

self.addEventListener('fetch', function (event) {

    // use the page skeleton from the cache

    let requestUrl = new URL(event.request.url);

    if(requestUrl.origin === location.origin){

        if(requestUrl.pathname === '/'){

            event.respondWith(

                caches.match('/skeleton')

            );

            return;

        }

    }

    event.respondWith(

        caches.match(event.request).then(function (response) {

            return response || fetch(event.request);

        })

    );

});