WebTransportDatagramDuplexStream: outgoingHighWaterMark property

Baseline 2026

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Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

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The outgoingHighWaterMark property of the WebTransportDatagramDuplexStream interface gets or sets the high water mark for outgoing chunks of data — this is the maximum size, in chunks, that the outgoing WritableStream's internal queue can reach before it is considered full. See Internal queues and queuing strategies for more information.

Value

A number.

Examples

const url = "https://example.com:4999/wt";

async function initTransport(url) {
  // Initialize transport connection
  const transport = new WebTransport(url);

  // The connection can be used once ready fulfills
  await transport.ready;

  const datagrams = transport.datagrams;

  // set outgoingHighWaterMark
  datagrams.outgoingHighWaterMark = 20000;

  // get outgoingHighWaterMark
  console.log(datagrams.outgoingHighWaterMark);
}