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.

Fixes #44273

[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: 2026-06-16 00:01:19)

[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.

[hamishwillee]

@chrisdavidmills I have reapplied all your suggestions. Should be ready for another look now.

[chrisdavidmills]

@hamishwillee, OK, this seems good to go, except for the weird issue I slacked you about concerning the code listing that seems broken in https://pr44383.review.mdn.allizom.net/en-US/docs/Web/API/WebTransport/datagrams#examples (the page no longer seems listed in the list of changed files.)

[hamishwillee]

@hamishwillee, OK, this seems good to go, except for the weird issue I slacked you about concerning the code listing that seems broken in https://pr44383.review.mdn.allizom.net/en-US/docs/Web/API/WebTransport/datagrams#examples (the page no longer seems listed in the list of changed files.)

@chrisdavidmills Thanks for the review!

Looking at the odd PR output it appears to have been caused by a missing end to a code block - I can't explain why this isn't being generated, but I can confirm the source markup is fine and the local rendering does not have this flaw.