WebTransportSendStream: sendOrder property

Limited availability

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

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is available in Web Workers.

The sendOrder property of the WebTransportSendStream interface indicates the send priority of this stream relative to other streams for which the value has been set.

Queued bytes are sent first for streams that have a higher value. If not set, the send order depends on the implementation.

Value

A number indicating the relative priority of this stream when sending bytes.

Examples

The example below shows how you can set the initial sendOrder when calling WebTransport.createUnidirectionalStream() to create the send stream, read the value from the stream, and then change the order. After changing the order the priority of this stream would increase, becoming higher than any stream with a priority of less than "596996858".

js
async function writeData() {
  const stream = await transport.createUnidirectionalStream({
    sendOrder: "400", // Set initial stream order
  });

  console.log(`Stream order: ${stream.sendOrder}`); // Stream order: 400

  // write data ...

  // Change the stream order
  stream.sendOrder = 596996858;
  console.log(`Stream order: ${stream.sendOrder}`); // Stream order: 596996858

  // write more data ...
}

Specifications

Specification
WebTransport
# dom-webtransportsendstream-sendorder

Browser compatibility

desktop mobile server
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
sendOrder
Chrome – No support
Chrome
footnote No support
Edge – No support
Edge
footnote No support
Firefox – Full support
Firefox 121 (Release date: 2023-12-19)
footnote Full support
Opera – No support
Opera
footnote No support
Safari – Full support
Safari 26.4 (Release date: 2026-03-24)
footnote Full support
Chrome Android – No support
Chrome Android
footnote No support
Firefox for Android – Full support
Firefox for Android 121 (Release date: 2023-12-19)
footnote Full support
Opera Android – No support
Opera Android
footnote No support
Safari on iOS – Full support
Safari on iOS 26.4 (Release date: 2026-03-24)
footnote Full support
Samsung Internet – No support
Samsung Internet
footnote No support
WebView Android – No support
WebView Android
footnote No support
WebView on iOS – Full support
WebView on iOS 26.4 (Release date: 2026-03-24)
footnote Full support
Deno – No support
Deno 2.2 (Release date: 2025-02-19)
disabled
disabled From version 2.2 users must explicitly set the --unstable-net runtime flag.

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
User must explicitly enable this feature.

See also