• Host: Sony
• Dates and times:
  • 10:00 to 17:00 JST (Asia/Tokyo) on Tuesday 29 September 2026
  • 10:00 to 17:00 JST (Asia/Tokyo) on Wednesday 30 September 2026
  • 10:00 to 16:00 JST (Asia/Tokyo) on Thursday 1 October 2026
• Location: Tokyo, Japan
• Attendee information: https://github.com/tc39/Reflector/issues/586
• Total duration of scheduled discussions:
  • Estimated meeting capacity: 15:00h _{This is an estimate: if you want to add a topic to the agenda, do not let this number stop you!}

gantt
  1 month before the meeting: milestone, 2026-08-29 10:00+0900, 1m
  Proposal advancement deadline: milestone, 2026-09-19 10:00+0900, 1m
  Schedule constraint deadline: milestone, 2026-09-26 10:00+0900, 1m
  Day 1 : day1, 2026-09-29 10:00+0900, 7h
  Day 2 : day2, 2026-09-30 10:00+0900, 7h
  Day 3 : day3, 2026-10-01 10:00+0900, 7h
  todayMarker stroke-width:5px,stroke:#0f0,opacity:0.5

For meeting times in your timezone, visit Temporal docs and run the code below in the devtools console.

Temporal.ZonedDateTime.from('2026-09-29T10:00[Asia/Tokyo]')
  .withTimeZone(Temporal.Now.timeZoneId()) // your time zone
  .toLocaleString();

Background:

• Allen Wirfs-Brock's paper on standards committee participation for new attendees
• TC39's documentation on How to participate in meetings

Deadline for advancement eligibility: September 19th 10:00 Asia/Tokyo

• _{Note: this time is selected to be precisely 10 days prior to the start of the meeting}

1. Proposals not looking to advance may be added at any time; if after the deadline, please always use a pull request so that members are notified of changes. Note: an unmerged PR counts as “added” for the purposes of this requirement.
2. Proposals seeking feedback at stage 0 must be added (and noted as such) prior to the deadline, or else delegates may object to advancement solely on the basis of missing the deadline.
   1. Such proposals should include supporting materials when possible.
3. Proposals looking to advance to stage 1 must be added (and noted as such) prior to the deadline, or else delegates may object to advancement solely on the basis of missing the deadline.
   1. Such proposals must link to a proposal repository and they should link to supporting materials when possible.
4. Proposals looking to advance to stages 2, 2.7, 3, or 4, as well as other normative changes to the standard or proposals in stage 3 or later looking to achieve consensus, must be added (and noted as such) along with links to the supporting materials prior to the deadline, or else delegates may withhold consensus for advancement solely on the basis of missing the deadline.
   1. If the supporting materials change substantially after the deadline, delegates may withhold consensus for advancement, based on the committee’s judgment.
   2. For urgent normative changes, the committee is expected to be more forgiving of a missed deadline, since there is generally less material to review than in a stage advancement.
   3. Proposals looking to advance to stage 4 must link to a pull request into the spec, since the process requires one.
5. Proposal-based agenda items should be sorted primarily by stage (descending), secondarily by timebox (ascending), and finally by insertion date.

Supporting materials includes slides, a link to the proposal repository, a link to spec text, etc.; essentially, anything you are planning to present to the committee, or that would be useful for delegates to review.

When applicable, use these emoji as a prefix to the agenda item topic.

1. Opening, welcome and roll call (Chair, 10m)

   1. Opening of the meeting
   2. TC39 follows its Code of Conduct
   3. Introduction of attendees
   4. Host facilities, local logistics
   5. Quick recap of meeting IPR policy
   6. Overview of communication tools
   7. Reminder to review Github Delegate teams (Jordan Harband)
   8. TC39 stenography support and legal disclaimer

2. Find volunteers for note taking

3. Adoption of the agenda

4. Approval of the minutes from last meeting

5. Next meeting host and logistics

6. Secretary's Report (15m, Samina Husain)

7. Addition of Eemeli Aro as an ECMA-402 editor (10m, Richard Gibson)

8. Project Editors’ Reports

   1. ECMA262 Status Updates (slides) (5m)
   2. ECMA402 Status Updates (5m)
   3. ECMA404 Status Updates (see tc39/Reflector#587) (10m)
   4. Test262 Status Updates (5m)

9. Task Group Reports

   1. TG3: Security (1m)
   2. TG4: Source Maps (5m)
   3. TG5: Experiments in Programming Language Standardization (5m)

10. Updates from the CoC Committee (1m)

11. Web compatibility issues / Needs Consensus PRs

    timebox	topic	presenter
    20m	Needs-consensus PR: make DataView.prototype.{byteLength,byteOffset} not throw when backed by detached buffer (PR, slides)	Kevin Gibbons
    20m	Normative: Update RevalidateAtomicAccess to account for all bytes of a TypedArray element	Richard Gibson
    30m	Normative: Make tail-call optimization normative-optional	Richard Gibson
    45m	Normative: Change KeptAlive semantics to strongify particular WeakRefs	Keith Miller
    2m	[TG2] Needs-consensus PR: Allow Locale.p.getNumberingSystems to return > 1 items	Jesse Alama
    2m	[TG2] Needs-consensus PR: Determine getWeekInfo().firstDay using First Day Overrides	Jesse Alama
    2m	[TG2] Needs-consensus PR: Define %TypedArray%.prototype.toLocaleString	Jesse Alama

12. Overflow from previous meeting

    timebox	topic	presenter

13. Short (≤30m) Timeboxed Discussions

    timebox	topic	presenter
    10m	update on TC39 data repo and proposal status tracking	Michael Ficarra, Jordan Harband
    15m	seeking consensus for update to AI policy for assistive technology - PR	Chris de Almeida

14. Proposals

    stage	timebox	topic	presenter
    3	5m	Iterator Join for Stage 4 (PR, implementation status)	Kevin Gibbons
    3	7m	Iterator Includes for Stage 4 (PR, slides)	Michael Ficarra
    3	8m	Iterator Chunking for Stage 4 (PR, slides)	Michael Ficarra
    3	9m	Dynamic Code Brand Checks for Stage 4 (PR, slides)	Nicolò Ribaudo
    3	30m	Disallow Adding New Private Fields to Non-extensible Objects PR#12	Olivier Flückiger
    2.7	30m	ESM Phase Imports normative PRs for Module source identity and Non-injective source imports	Guy Bedford
    2.7	30m	Thenable Curtailment for Stage 3 (Test 262 PR, Slides)	Matthew Gaudet
    2	20m	Intl Sequence Units Stage 2 Update (slides TBD)	Shane F Carr
    2	20m	Intl Unit Protocol Stage 2 Update (slides TBD)	Shane F Carr
    2	30m	Amount Stage 2 Update (slides)	Jesse Alama
    2	30m	export defer for Stage 2.7 (slides)	Nicolò Ribaudo & Caio Lima
    2	30m	JSON.parse Options for Stage 2.7 ([slides])(https://docs.google.com/presentation/d/1xNMjd3p8wo4NqtuBCOu-We_lFWX0SWI36721xmjlSHQ)	Peter Klecha & Ashley Claymore
    2	120m	Async iterators: the whole proposal + open questions (timebox can be split)	Kevin Gibbons
    1	20m	Include default in export * for Stage 2 & 2.7 (slides)	Nicolò Ribaudo
    1	30m	Bigint from exponential for Stage 2	Richard Gibson
    1	30m	Private declarations for Stage 2 (slides)	Kevin Gibbons
    1	60m	Composites for Stage 2 (draft spec, slides)	Ashley Claymore
    0	28m	Pulling in AbortController for Stage 1 or something (slides)	Kevin Gibbons

15. Longer or open-ended discussions

    timebox	topic	presenter
    60m	reworking Cover and Supplemental Grammars (slides, draft spec)	Mikhail Barash
    60m	It's about the agenda deadline (slides)	Chris de Almeida
    60m	It's about the AI policy (wrestling with ambiguities, expectations, intent, and permissible usage)	Chris de Almeida

16. Overflow from timeboxed agenda items (in insertion order)

    topic	presenter

1. Other business
   1. Thank host
2. Adjournment

Schedule constraints should be supplied here as soon as possible, and at least three days before the meeting begins so that the Chairs can take them into account when preparing the schedule.

• Kevin Gibbons (KG) would prefer not to present after 15:00 JST.
• Nicolò Ribaudo would prefer Include default in export * to precede export defer. I very strongly prefer to present after 15:00; if I need to present earlier I need to know the day before (and still, even if before 15:00 later is better).
• Guy Bedford is only available to present from 10am - 12pm JST on the last day. He will also be attending from in-flight WiFi during the first day except for the last hour.
• Matthew Gaudet is only available to present from 10am to 12pm JST, after the first day.