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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 15.5k 1.4k

  2. ecma402 ecma402 Public

    Status, process, and documents for ECMA 402

    HTML 589 113

  3. test262 test262 Public

    Official ECMAScript Conformance Test Suite

    JavaScript 2.6k 515

  4. proposals proposals Public

    Tracking ECMAScript Proposals

    19k 738

  5. agendas agendas Public

    TC39 meeting agendas

    JavaScript 1.2k 198

  6. notes notes Public

    TC39 meeting notes

    JavaScript 696 125

Repositories

Showing 10 of 315 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 3,628 169 29 11 Updated Dec 6, 2025
  • dataset Public

    The automatic track tc39 proposals

    tc39/dataset’s past year of commit activity
    TypeScript 45 Unlicense 11 2 0 Updated Dec 6, 2025
  • how-we-work Public

    Documentation of how TC39 operates and how to participate

    tc39/how-we-work’s past year of commit activity
    215 29 23 10 Updated Dec 5, 2025
  • test262 Public

    Official ECMAScript Conformance Test Suite

    tc39/test262’s past year of commit activity
    JavaScript 2,647 515 213 (4 issues need help) 66 Updated Dec 5, 2025
  • ecma402 Public

    Status, process, and documents for ECMA 402

    tc39/ecma402’s past year of commit activity
    HTML 589 113 157 10 Updated Dec 5, 2025
  • ecma262 Public

    Status, process, and documents for ECMA-262

    tc39/ecma262’s past year of commit activity
  • proposals Public

    Tracking ECMAScript Proposals

    tc39/proposals’s past year of commit activity
    19,003 738 6 3 Updated Dec 4, 2025
  • tc39.github.io Public

    Get involved in specifying JavaScript

    tc39/tc39.github.io’s past year of commit activity
    HTML 331 MIT 61 27 (3 issues need help) 2 Updated Dec 4, 2025
  • ecma426 Public

    Source map specification, RFCs and new proposals.

    tc39/ecma426’s past year of commit activity
    JavaScript 173 22 62 8 Updated Dec 3, 2025
  • proposal-nonextensible-applies-to-private Public

    Proposal to disallow adding new private fields to non-extensible objects

    tc39/proposal-nonextensible-applies-to-private’s past year of commit activity
    JavaScript 8 MIT 1 4 0 Updated Nov 28, 2025