可选body可选cacheA string indicating how the request will interact with the browser's cache to set request's cache.
可选credentialsA string indicating whether credentials will be sent with the request always, never, or only when sent to a same-origin URL. Sets request's credentials.
可选headersA Headers object, an object literal, or an array of two-item arrays to set request's headers.
可选integrityA cryptographic hash of the resource to be fetched by request. Sets request's integrity.
可选keepaliveA boolean to set request's keepalive.
可选methodA string to set request's method.
可选modeA string to indicate whether the request will use CORS, or will be restricted to same-origin URLs. Sets request's mode.
可选redirectA string indicating whether request follows redirects, results in an error upon encountering a redirect, or returns the redirect (in an opaque fashion). Sets request's redirect.
可选referrerA string whose value is a same-origin URL, "about:client", or the empty string, to set request's referrer.
可选referrerA referrer policy to set request's referrerPolicy.
可选signalAn AbortSignal to set request's signal.
可选windowCan only be null. Used to disassociate request from any Window.
A BodyInit object or null to set request's body.