What a transport resolves with. The engine also accepts what a fetch-based transport naturally returns: headers as a Headers object, a Map or a record in any case, and body as any ArrayBuffer view (a Uint8Array, from any realm) or an ArrayBuffer.
fetch
headers
Headers
Map
body
ArrayBuffer
Uint8Array
What a transport resolves with. The engine also accepts what a
fetch-based transport naturally returns:headersas aHeadersobject, aMapor a record in any case, andbodyas anyArrayBufferview (aUint8Array, from any realm) or anArrayBuffer.