Request: duplex property

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The duplex read-only property of the 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

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