Seonglae ChoThe Content Indexing API is not an alternative way of caching content
It's a way of providing metadata about pages that are already cached by your service worker
so it has dependency to service worker
Indexing your offline-capable pages with the Content Indexing API
Your PWA might cache articles and media files, but how will your users know that your pages work while offline? The Content Indexing API is one answer to this question. Once the index is populated with content from your PWA, as well as any other installed PWAs, it will show up in dedicated areas of supported browsers.
https://web.dev/content-indexing-api/
