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@tc39

Ecma TC39

Ecma International, Technical Committee 39 - ECMAScript

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TC39

Ecma International's TC39 is a group of JavaScript developers, implementers, academics, and more, collaborating with the community to maintain and evolve the definition of JavaScript.

Contribute

TC39 welcomes contributions from the JavaScript community, whether it is feedback on existing proposals, improved documentation, testing, implementations, or even language feature ideas. See our contributor guide for details.

Important

To participate in TC39 meetings as a member, join Ecma.

Specifications

We develop the JavaScript (formally, ECMAScript) specification, the Internationalization API specification, the Source Map specification, and, of course, JSON! We meet every two months to discuss proposals. To learn more about the process, please take a look at the six stages for new language feature proposals. See our meeting agendas and minutes to learn more.

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  1. ecma262 ecma262 Public

    Status, process, and documents for ECMA-262

    HTML 15.6k 1.4k

  2. ecma402 ecma402 Public

    Status, process, and documents for ECMA 402

    HTML 592 114

  3. test262 test262 Public

    Official ECMAScript Conformance Test Suite

    JavaScript 2.7k 520

  4. proposals proposals Public

    Tracking ECMAScript Proposals

    19k 736

  5. agendas agendas Public

    TC39 meeting agendas

    JavaScript 1.2k 199

  6. notes notes Public

    TC39 meeting notes

    JavaScript 698 125

Repositories

Showing 10 of 317 repositories
  • proposal-temporal Public

    Provides standard objects and functions for working with dates and times.

    tc39/proposal-temporal’s past year of commit activity
    HTML 3,637 171 29 31 Updated Jan 9, 2026
  • proposal-first-class-protocols Public

    a proposal to bring protocol-based interfaces to ECMAScript users

    tc39/proposal-first-class-protocols’s past year of commit activity
    JavaScript 360 MIT 8 20 0 Updated Jan 9, 2026
  • dataset Public

    The automatic track tc39 proposals

    tc39/dataset’s past year of commit activity
    TypeScript 45 Unlicense 11 2 0 Updated Jan 9, 2026
  • proposal-amount Public

    Numbers with precision and a unit for JavaScript

    tc39/proposal-amount’s past year of commit activity
    HTML 40 MIT 8 32 3 Updated Jan 8, 2026
  • agendas Public

    TC39 meeting agendas

    tc39/agendas’s past year of commit activity
    JavaScript 1,166 199 0 2 Updated Jan 8, 2026
  • proposal-intl-unit-format Public

    `Intl.UnitFormat` specification [draft]

    tc39/proposal-intl-unit-format’s past year of commit activity
    HTML 9 3 5 0 Updated Jan 8, 2026
  • tc39/proposal-deferred-reexports’s past year of commit activity
    43 MIT 5 7 2 Updated Jan 8, 2026
  • test262 Public

    Official ECMAScript Conformance Test Suite

    tc39/test262’s past year of commit activity
    JavaScript 2,658 520 206 (4 issues need help) 83 Updated Jan 8, 2026
  • tc39/source-map-tests’s past year of commit activity
    JavaScript 10 10 7 0 Updated Jan 7, 2026
  • proposal-intl-era-monthcode Public

    To specify necessary details about era, eraYear and monthCode usage with Temporal for non-ISO calendars.

    tc39/proposal-intl-era-monthcode’s past year of commit activity
    HTML 5 MIT 8 16 9 Updated Jan 7, 2026