send_early_hints

Early Hints is an HTTP/2 status code that indicates hints to help a client start making preparations for processing the final response.

If the env contains rack.early_hints then the server accepts HTTP2 push for Link headers.

The send_early_hints method accepts a hash of links as follows:

send_early_hints("Link" => "</style.css>; rel=preload; as=style\n</script.js>; rel=preload")

If you are using javascript_include_tag or stylesheet_link_tag the Early Hints headers are included by default if supported.