@s8/static-tm/public/service-worker-custom.js

Static module for Trinity Mirror partner.

const staticAssets = [
  './shopping',
  './shopping/placeholder.png'
]

self.addEventListener('install', async event => {
  const cache = await caches.open('static')
  cache.addAll(staticAssets)
})

self.addEventListener('fetch', async event => {
  const req = event.request
  const url = new URL(req.url)
  if (
    (url.host === 'www.google-analytics.com') ||
    (url.pathname === '/r/collect') ||
    (url.pathname === '/shopping/graphql')
  ) {
    event.respondWith(networkOnly(req))
  } else {
    if (url.origin === location.origin) {
      event.respondWith(cacheFirst(req))
    } else {
      event.respondWith(networkFirst(req))
    }
  }
})

async function networkOnly (req) {
  try {
    const res = await fetch(req)
    return res
  } catch (error) {
    return new Response('Offline', {'status': 200})
  }
}

async function networkFirst (req) {
  const cache = await caches.open('dynamic')
  try {
    const res = await fetch(req)
    cache.put(req, res.clone())
    return res
  } catch (error) {
    const cachedResponse = await cache.match(req)
    return cachedResponse || caches.match('./shopping/placeholder.png')
  }
}

async function cacheFirst (req) {
  const cachedResponse = await caches.match(req)
  let networkResponse
  try {
    networkResponse = await fetch(req)
  } catch (error) {
    networkResponse = caches.match('./shopping/placeholder.png')
    return networkResponse
  }
  return cachedResponse || networkResponse
}