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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 526

  4. proposals proposals Public

    Tracking ECMAScript Proposals

    19.1k 739

  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
  • test262 Public

    Official ECMAScript Conformance Test Suite

    tc39/test262’s past year of commit activity
    JavaScript 2,676 526 210 (4 issues need help) 85 Updated Feb 23, 2026
  • tc39/proposal-deferred-reexports’s past year of commit activity
    50 MIT 5 7 2 Updated Feb 23, 2026
  • dataset Public

    The automatic track tc39 proposals

    tc39/dataset’s past year of commit activity
    TypeScript 47 Unlicense 11 2 0 Updated Feb 23, 2026
  • ecma262 Public

    Status, process, and documents for ECMA-262

    tc39/ecma262’s past year of commit activity
    HTML 15,586 1,390 357 (10 issues need help) 115 Updated Feb 22, 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 13 Updated Feb 22, 2026
  • test262-harness Public

    Experimental harness for test262

    tc39/test262-harness’s past year of commit activity
    JavaScript 93 BSD-3-Clause 46 14 7 Updated Feb 22, 2026
  • ecma426 Public

    Source map specification, RFCs and new proposals.

    tc39/ecma426’s past year of commit activity
    JavaScript 176 26 63 7 Updated Feb 20, 2026
  • tc39.github.io Public

    Get involved in specifying JavaScript

    tc39/tc39.github.io’s past year of commit activity
    HTML 331 MIT 61 28 (3 issues need help) 2 Updated Feb 20, 2026
  • proposal-amount Public

    Numbers with precision and a unit for JavaScript

    tc39/proposal-amount’s past year of commit activity
    HTML 43 MIT 8 34 3 Updated Feb 20, 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 5 0 Updated Feb 20, 2026