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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 595 114

  3. test262 test262 Public

    Official ECMAScript Conformance Test Suite

    JavaScript 2.7k 525

  4. proposals proposals Public

    Tracking ECMAScript Proposals

    19.1k 740

  5. agendas agendas Public

    TC39 meeting agendas

    JavaScript 1.2k 200

  6. notes notes Public

    TC39 meeting notes

    JavaScript 700 126

Repositories

Showing 10 of 322 repositories
  • ecma402 Public

    Status, process, and documents for ECMA 402

    tc39/ecma402’s past year of commit activity
    HTML 595 114 159 7 Updated Feb 19, 2026
  • proposal-temporal Public

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

    tc39/proposal-temporal’s past year of commit activity
    HTML 3,657 172 20 5 Updated Feb 19, 2026
  • agendas Public

    TC39 meeting agendas

    tc39/agendas’s past year of commit activity
    JavaScript 1,167 200 0 2 Updated Feb 19, 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 6 MIT 9 6 1 Updated Feb 19, 2026
  • proposal-amount Public

    Numbers with precision and a unit for JavaScript

    tc39/proposal-amount’s past year of commit activity
    HTML 42 MIT 8 33 5 Updated Feb 19, 2026
  • dataset Public

    The automatic track tc39 proposals

    tc39/dataset’s past year of commit activity
    TypeScript 47 Unlicense 11 2 0 Updated Feb 19, 2026
  • tg5 Public

    TC39-TG5: Experiments in programming language standardization. https://ecma-international.org/task-groups/tc39-tg5/

    tc39/tg5’s past year of commit activity
    26 3 28 (6 issues need help) 0 Updated Feb 18, 2026
  • test262 Public

    Official ECMAScript Conformance Test Suite

    tc39/test262’s past year of commit activity
    JavaScript 2,669 525 209 (4 issues need help) 85 Updated Feb 18, 2026
  • tc39/proposal-intl-keep-trailing-zeros’s past year of commit activity
    3 MIT 1 1 1 Updated Feb 18, 2026
  • ecmarkup Public

    An HTML superset/Markdown subset source format for ECMAScript and related specifications

    tc39/ecmarkup’s past year of commit activity
    TypeScript 236 MIT 74 101 12 Updated Feb 18, 2026