It doesn't index each resource. Only the page text of the URLs you actually navigate to in a tab. So this is fine. It won't index a JSON response in an SPA, as

It doesn't index each resource. Only the page text of the URLs you actually navigate to in a tab. So this is fine. It won't index a JSON response in an SPA, as search result (tho it does save it), but it will index (and re index) the actual page content, as you browse it and as it updates (eg dynamically loads in an SPA). Try it out, you'll have an easier time understanding how it works (as long as the current tag release works, heh :) if not try a previous tag).