is it possible to modify service worker cache response headers?

Question

I am trying to mark resources that are being stored in the service worker cache.

I thought it would be possible to add a custom header to the resource that could indica

Answer 1

You would have to create a new response to do this:

fetch('./').then(response => {
  console.log(new Map(response.headers));

  const newHeaders = new Headers(response.headers);
  newHeaders.append('x-foo', 'bar');

  const anotherResponse = new Response(response.body, {
    status: response.status,
    statusText: response.statusText,
    headers: newHeaders
  });

  console.log(new Map(anotherResponse.headers));
});

Live demo (see the console)