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WebTransport: incomingUnidirectionalStreams property

The incomingUnidirectionalStreams read-only property of the WebTransport interface represents one or more unidirectional streams opened by the server. Returns a ReadableStream of WebTransportReceiveStream objects. Each one can be used to reliably read data from the server.

"Reliable" means that transmission and order of data are guaranteed. This provides slower delivery (albeit faster than with WebSockets) than datagrams, but is needed in situations where reliability and ordering are important, like chat applications.

Note: This feature is available in Web Workers

Value

Examples

An initial function is used to read the WebTransportReceiveStream objects from the ReadableStream. Each object is then passed to another function to read from those streams.

js

async function receiveUnidirectional() {
  const uds = transport.incomingUnidirectionalStreams;
  const reader = uds.getReader();
  while (true) {
    const { done, value } = await reader.read();
    if (done) {
      break;
    }
    // value is an instance of WebTransportReceiveStream
    await readData(value);
  }
}

async function readData(receiveStream) {
  const reader = receiveStream.getReader();
  while (true) {
    const { done, value } = await reader.read();
    if (done) {
      break;
    }
    // value is a Uint8Array
    console.log(value);
  }
}

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
incomingUnidirectionalStreams 97 97 114 No 83 No 97 97 114 68 No 18.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/WebTransport/incomingUnidirectionalStreams