Snippet to get the total size of everything in the Cache Storage API for the current origin

totalCacheSize.js

async function totalCacheSize() {
  let size = 0;
  const cacheNames = await caches.keys();
  for (const cacheName of cacheNames) {
    const cache = await caches.open(cacheName);
    const cachedRequests = await cache.keys();
    for (const cachedRequest of cachedRequests) {
      const cachedResponse = await cache.match(cachedRequest);
      const responseBlob = await cachedResponse.blob();
      size += responseBlob.size;
    }
  }
  return totalContentSize;
}

// Can the be used in the JS console:
// totalContentSize().then(console.log);