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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 15.7k 1.4k

  2. ecma402 ecma402 Public

    Status, process, and documents for ECMA 402

    HTML 612 122

  3. test262 test262 Public

    Official ECMAScript Conformance Test Suite

    JavaScript 2.8k 571

  4. proposals proposals Public

    Tracking ECMAScript Proposals

    19.2k 748

  5. agendas agendas Public

    TC39 meeting agendas

    JavaScript 1.2k 200

  6. notes notes Public

    TC39 meeting notes

    JavaScript 714 128

Repositories

Showing 10 of 338 repositories
  • proposal-intl-sequence-units Public

    Support for CLDR mixed units, like "5ft 6in"

    tc39/proposal-intl-sequence-units's past year of commit activity
    JavaScript 1 MIT 1 6 1 Updated Nov 14, 2026
  • proposal-intl-eradisplay Public

    Intl.DateTimeFormat displays era field only if date displayed is in same era as today's

    tc39/proposal-intl-eradisplay's past year of commit activity
    11 MIT 1 5 1 Updated Nov 14, 2026
  • agendas Public

    TC39 meeting agendas

    tc39/agendas's past year of commit activity
    JavaScript 1,175 200 2 4 Updated Nov 14, 2026
  • tc39/proposal-esm-phase-imports's past year of commit activity
    HTML 53 MIT 4 5 3 Updated Nov 14, 2026
  • ecma426 Public

    Source map specification, RFCs and new proposals.

    tc39/ecma426's past year of commit activity
    JavaScript 188 33 78 11 Updated Nov 14, 2026
  • dataset Public

    The automatic track tc39 proposals

    tc39/dataset's past year of commit activity
    TypeScript 49 Unlicense 13 2 1 Updated Nov 14, 2026
  • ecma402 Public

    Status, process, and documents for ECMA 402

    tc39/ecma402's past year of commit activity
    HTML 612 122 173 12 Updated Nov 13, 2026
  • proposal-fma Public

    Fused Multiply Add

    tc39/proposal-fma's past year of commit activity
    JavaScript 9 MIT 2 5 0 Updated Nov 13, 2026
  • ecma262 Public

    Status, process, and documents for ECMA-262

    tc39/ecma262's past year of commit activity
    HTML 15,703 1,428 364 (8 issues need help) 124 Updated Nov 13, 2026
  • proposal-immutable-arraybuffer Public

    A TC39 proposal for immutable ArrayBuffers

    tc39/proposal-immutable-arraybuffer's past year of commit activity
    JavaScript 40 MIT 7 7 0 Updated Nov 13, 2026