title: What limitations apply to opaque responses?
body: <p><a href="https://fetch.spec.whatwg.org/#concept-filtered-response-opaque">Opaque responses</a> are defined as part of the <a href="https://fetch.spec.whatwg.org/">Fetch API</a>, and represent the result of a request made to a remote origin when <a href="https://fetch.spec.whatwg.org/#http-cors-protocol">CORS</a> is not enabled.</p>
  
  <p>What practical limitations and "gotchas" exist around how opaque responses can be used, both from JavaScript and as resources on a page?</p>