I am trying to add links to my assets in workbox service worker to cache. And I want them to load from cache then look to the network. I am new to workbox so I dont know what to do. Please help. Here's the workbox code.

importScripts('/local-res/comps/wb-ox-sw.js');
'use strict';
var cacheVersion = 1,
    currentCache = {
  offline: 'OFFSERVE' + cacheVersion
},
offlineUrl = '/mes_srv_off.html';

this.addEventListener('install', event => {
  event.waitUntil(
    caches.open(currentCache.offline).then(function(cache) {
      return cache.addAll([
        offlineUrl  
      ]);
    })
  );
});

this.addEventListener('fetch', event => {
  if (event.request.mode === 'navigate' || (event.request.method === 'GET' && event.request.headers.get('accept').includes('text/html'))) {
        event.respondWith(
          fetch(event.request.url).catch(error => {
              return caches.match(offlineUrl);
          })
    );
  }
  else{
        event.respondWith(caches.match(event.request)
                        .then(function (response) {
                        return response || fetch(event.request);
                    })
            );
      }
});

workbox.routing.registerRoute(
  ({request}) => request.destination === 'image',
  new workbox.strategies.CacheFirst()
);
workbox.routing.registerRoute(
  ({request}) => request.destination === 'style' ||
    request.destination === 'script',
  new workbox.strategies.CacheFirst()
);