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Request: duplex property

files/en-us/web/api/request/duplex/index.md

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{{APIRef("Fetch API")}}{{SeeCompatTable}}

The duplex read-only property of the {{domxref("Request")}} interface returns the duplex mode of the request, which determines whether the browser must send the entire request before processing the response.

Value

A string with the following possible value:

  • "half"
    • : The browser must send the entire request before processing the response.

Notes

Although duplex can be passed as an option when constructing a Request, it is not currently exposed as a readable property on the resulting Request object in all browsers.

Examples

Checking a request's duplex mode

js
const stream = new ReadableStream({
  /* ... */
});
const request = new Request("/upload", {
  method: "POST",
  body: stream,
  duplex: "half", // Required for streaming requests
});

console.log(request.duplex); // "half"

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also