WebTransportDatagramsWritable and friends

[hamishwillee]

This documents most of the new WebTransport support for prioritizing streams/datagrams within a sendGroup based on sendOrder for the respective stream objects - such as WebTransportDatagramsWritable. This is recently implemented in Safari.

I started on this when reviewing #44317 because that wants to refer to an undocumented method I needed to understand. Talking about pulling a thread...

Anyway, I believe this is correct and useful. The only thing missing is the stream equivalent of WebTransportDatagramsWritable - WebTransportSendStream.

[github-actions]

Preview URLs (9 pages)

• /en-US/docs/Web/API/WebTransport/createSendGroup
• /en-US/docs/Web/API/WebTransportDatagramDuplexStream/createWritable
• /en-US/docs/Web/API/WebTransportDatagramDuplexStream
• /en-US/docs/Web/API/WebTransportDatagramsWritable/sendGroup
• /en-US/docs/Web/API/WebTransportDatagramsWritable/sendOrder
• /en-US/docs/Web/API/WebTransportDatagramsWritable
• /en-US/docs/Web/API/WebTransportSendGroup/getStats
• /en-US/docs/Web/API/WebTransportSendGroup
• /en-US/docs/Web/API/WebTransport

External URLs (7)

URL: /en-US/docs/Web/API/WebTransport/createSendGroup
Title: WebTransport: createSendGroup() method

• https://developer.chrome.com/docs/capabilities/web-apis/webtransport (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/WebTransportDatagramDuplexStream/createWritable
Title: WebTransportDatagramDuplexStream: createWritable() method

• https://developer.chrome.com/docs/capabilities/web-apis/webtransport (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/WebTransportDatagramsWritable
Title: WebTransportDatagramsWritable

• https://developer.chrome.com/docs/capabilities/web-apis/webtransport (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/WebTransportDatagramsWritable/sendGroup
Title: WebTransportDatagramsWritable: sendGroup property

• https://developer.chrome.com/docs/capabilities/web-apis/webtransport (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/WebTransportDatagramsWritable/sendOrder
Title: WebTransportDatagramsWritable: sendOrder property

• https://developer.chrome.com/docs/capabilities/web-apis/webtransport (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/WebTransportSendGroup
Title: WebTransportSendGroup

• https://developer.chrome.com/docs/capabilities/web-apis/webtransport (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/WebTransportSendGroup/getStats
Title: WebTransportSendGroup: getStats() method

• https://developer.chrome.com/docs/capabilities/web-apis/webtransport (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2026-06-09 06:12:12)

[chrisdavidmills]

Hi @hamishwillee! I've read through all of these and provided some commentary. Looking mostly pretty good and makes sense.

[hamishwillee]

Thanks @chrisdavidmills - Accepted almost all of them. Should be good for another look.

[github-actions]

[mdn-linter] _{reported by reviewdog 🐶}

Suggested change

	typeof transport.datagrams.createWritable === "function"
	? transport.datagrams.createWritable()
	: transport.datagrams.writable; // Deprecated and non-standard
	typeof transport.datagrams.createWritable === "function"
	? transport.datagrams.createWritable()
	: transport.datagrams.writable; // Deprecated and non-standard

[github-actions]

[mdn-linter] _{reported by reviewdog 🐶}

Suggested change

	typeof transport.datagrams.createWritable === "function"
	? transport.datagrams.createWritable()
	: transport.datagrams.writable; // Deprecated and non-standard
	typeof transport.datagrams.createWritable === "function"
	? transport.datagrams.createWritable()
	: transport.datagrams.writable; // Deprecated and non-standard