headers

Request: Headers.

Provides a typed view of fetch headers on top of this request, via FetchHeaders, which behaves as a specialized JavaScript-compatible multi-map. Multiple header values can be set per header key, if desired, which can be safely combined into a comma-separated header value group upon render.

From MDN: "The headers read-only property of the Request interface contains the Headers object associated with the request."

See also: MDN, Request.headers.