service-worker.js

var cacheName = 'v1',
    checkinDataRegex = /applicable\?pnr=([a-zA-Z0-9]+)&lastname=([a-zA-Z]+)/
    ticketRegex = /image\/pnr\/([a-zA-Z0-9]+)\/lastname\/([a-zA-Z]+)\/ticket\/([0-9]+)/;

self.addEventListener('fetch', function(event) {
    var request = event.request,
        matchCheckin = checkinDataRegex.exec(request.url);
    if (matchCheckin) {
        // Use regex capturing to grab only the bit of the URL
        // that we care about (in this case the checkinID)
        var cacheRequest = new Request(match[1]);
        event.respondWith(
            caches.match(cacheRequest).then(function(response) {
                return response || fetch(request).then(function(response) {
                    caches.open(cacheName).then(function(cache) {
                      cache.put(cacheRequest, response);
                    })
                    return response;
                });
            })
        );
    }
    if (ticketRegex) { 
      // disable the image (by replacing it)
      [...]
    }
    [...]
});

// communication between the service worker and the app.js
self.addEventListener("message", function(event) {
 var data = event.data;
 switch(data.command) {
  case 'deleteCheckin':
    // open current cache
    caches.open(cacheName).then(function(cache) {
      // remove the flight data (JSON)
      cache.delete(data.checkinID).then(function(success) {
        event.ports[0].postMessage({
          error: success ? null : 'Item was not found in the cache.'
        });
      )};
    })
    break;
    [...]
 }
});