onionite/public/sw.js

var cacheName   = 'top-explorer-cache-v1';
var offlineUrl  = '/no-connection';

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

  // Cache assets
  event.waitUntil(
    caches.open(cacheName)
      .then(function(cache) {
        return cache.addAll([
          offlineUrl,
          '/about',
          '/assets/style.css',
          '/assets/enhancements.js',
          '/assets/iconfont.woff',
          '/assets/heart.svg'
        ]);
      })
  );
});

// Fetch
self.addEventListener('fetch', function(event) {
  var requestUrl = new URL(event.request.url);

  // Only do stuff with our own urls
  if(requestUrl.origin !== location.origin) {
    return;
  }

  // Try cache first for assets
  if(requestUrl.pathname.startsWith('/assets/')) {
    event.respondWith(
      caches.match(event.request)
        .then(function(response) {

          // If we don't have it make the request
          return response || fetch(event.request);
        }
      )
    );
    return;
  }

  // If we navigate to a page
  if(event.request.mode === 'navigate') {
    event.respondWith(

      // Make the request
      fetch(event.request)

        // Cache the response for certain pages
        .then(function(response) {
          if(requestUrl.pathname === '/' || requestUrl.pathname.startsWith('/node/')) {
            caches.open(cacheName).then(function(cache) {

              // Modify the response html so we know when it was cached
              response.clone().text().then(function(html) {
                html = html.replace('window.cacheDate=false;', 'window.cacheDate="'+Date()+'";');
                var modifiedResponse = new Response(new Blob([html]), { headers: response.headers });
                cache.put(event.request, modifiedResponse);
              });
            });
          }

          // Return the response as normal
          return response;
        })

        // If it fails
        .catch(function() {

          // Try and return a previously cached version
          return caches.match(event.request)
            .then(function(response) {

              // If we don't have a cached version show pretty offline page
              return response || caches.match(offlineUrl);
            });
        })
    );
  }
});