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Agenda for the 59th meeting of Ecma TC39

  • Host: Microsoft, Redmond, WA
  • Dates: 25-27 July 2017
  • Times:
    • 10:00 to 17:00 ET on 25 and 26 of July 2017
    • 10:00 to 16:00 ET on 27 of July 2017
  • Location:
    Microsoft Building 34 Room 1001 (Palouse)
    3720 159th Ave NE
    Redmond, WA 98052
  • Wifi: MSFTGuest
  • Dinner: Maggiano's 10455 NE 8th St, Bellevue, WA 98004 at 6:30PM
  • Contact:


Visitor parking is available in many locations around the venue. Follow the signs!

We will be in a restricted building. Visitors must be escorted at all times. When you arrive, notify reception and either Brian or another Microsoft employee will escort you to the meeting room.

Allen's paper on standards committee participation for new attendees:




No recommendations. Many are available. Check with your travel agent.

Agenda items

  1. Opening, welcome and roll call
    1. Opening of the meeting (Chair)
    2. Introduction of attendees
    3. Host facilities, local logistics
  2. Find volunteers for note taking
  3. Adoption of the agenda
  4. Approval of the minutes from last meeting
  5. Report from the Ecma Secretariat (15m)
  6. ECMA262 Status Updates (15m)
  7. ECMA402 Status Updates (15m)
  8. Test262 Status Updates (15m)
    1. Follow up: Use the default license file for tests files (Leo Balter)
    2. Using Frontmatter tags that matter (Leo Balter)
  9. Timeboxed overflow from previous meeting
    1. 15 Minute Items
    2. 30 Minute Items
    3. 45 Minute Items
    4. 60 Minute Items
      1. Cancellation (slides) (Ron Buckton)
      2. Module/script pragma, for stage 2 (proposal; slides) (Dave Herman, Yehuda Katz)
  10. Talks on visions for the future of ECMAScript (30 min limit)
    1. Extremely Modular Distributed JavaScript (Mark S. Miller)
    2. Vision Thing (Chip Morningstar)
    3. Vision Thing #2, or Expanding the vision of TC39. (Leo Balter)
    4. JavaScript - Composition and Compliance (Dean Tribble)
  11. Timeboxed agenda items
    1. 15 Minute Items
      1. Intl.Segmenter for Stage 3 (spec) (Daniel Ehrenberg)
      2. Fixing the spec logo to not be humongous (Domenic Denicola)
    2. 30 Minute Items
      1. Function.prototype.toString looking for stage 4 (Michael Ficarra)
      2. Symbol.prototype.description (Michael Ficarra)
      3. Promise.prototype.finally seeking stage 3 (Jordan Harband)
      4. Intl.RelativeTimeFormat for Stage 2 (Zibi Braniecki, Daniel Ehrenberg) (slides) (cut down to 20 minutes for Segmenter going over timebox)
      5. export-ns-from and export-default-from for Stage 2 (Ben Newman, John-David Dalton)
      6. Temporal Proposal updates (Maggie Pint)
      7. Numeric separators for Stage 2 (Sam Goto, Rick Waldron) (spec, slides)
    3. 45 Minute Items
      1. BigInt for Stage 3 (slides) (Daniel Ehrenberg)
      2. Array.prototype.flat{Map,ten} (slides) (Brian Terlson, Michael Ficarra)
    4. 60 Minute Items
      1. Optional catch binding (Michael Ficarra)
      2. Unified introduction of class features (Daniel Ehrenberg) (15 minutes)
      3. Class fields for Stage 3 (Jeff Morrison, Kevin Gibbons and Daniel Ehrenberg)
      4. Private methods and accessors for Stage 2 (Daniel Ehrenberg, Kevin Gibbons) (spec, presentation) (30 minutes)
      5. Interaction of privacy, fields and decorators (Yehuda Katz, Brian Terlson, and Daniel Ehrenberg) for Stage 2 (explainer, spec, presentation) (30 minutes)
  12. Non-timeboxed overflow from previous meeting
  13. Non-timeboxed agenda items
    1. Web compatibility issues / Needs-consensus PRs
      1. Caching template objects
      2. Order evaluation of Object Literals
    2. Stage 0+ proposals looking to advance
      1. Seeking stage-2 for Optional Chaining Operator (Gabriel Isenberg, Claude Pache) (explainer, spec, slides)
      2. Consider changing Number.parseInt and Number.parseFloat to avoid converting undefined, null, and NaN to string, returning NaN for those three input values. This fixes unexpected behavior for radix >= 24. (Brendan Eich)
    3. New proposals
      1. Interfaces (slides) (Michael Ficarra)
      2. Extensible literals (explainer, slides) (Daniel Ehrenberg) timebox: 20m (but please leave this far down on the agenda)
      3. Binary AST (slides) (Shu-yu Guo, Wed or Thurs morning for David Teller to call in)
      4. Pipeline operator (Backup champion: Daniel Ehrenberg) (explainer, backup presentation)
      5. Partial application (Ron Buckton)
      6. Throw expressions (Ron Buckton)
      7. Object Shorthand Improvements (Ron Buckton)
      8. Nullary coalescing operator (Gabriel Isenberg) (slides)
      9. Pattern Matching Updates (Brian Terlson)
    4. Discussion and updates for Stage 0+ Proposals
    5. Meeting schedule for 2018 (agenda item added by Adam Klein)
  14. Overflow from timeboxed discussion items (in insertion order)
  15. How should ECMA 402 proceed in light of "ICU standardization" concerns (Daniel Ehrenberg)
  16. Closure

Agenda Topic Rules

  1. Proposals looking to advance must be added to the agenda along with necessary review materials 7 days prior to the first day of the meeting.
  2. Timeboxed topics may be 15, 30, 45, or 60 minutes in length.

Schedule constraints

Dates and locations of future meetings

Dates Location Host
2017-09-26 to 2017-09-28 Boston, MA Bocoup
2017-11-28 to 2017-11-30 San Francisco, CA Airbnb