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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 597 115

  3. test262 test262 Public

    Official ECMAScript Conformance Test Suite

    JavaScript 2.7k 534

  4. proposals proposals Public

    Tracking ECMAScript Proposals

    19.1k 746

  5. agendas agendas Public

    TC39 meeting agendas

    JavaScript 1.2k 201

  6. notes notes Public

    TC39 meeting notes

    JavaScript 706 125

Repositories

Showing 10 of 324 repositories
  • test262-harness Public

    Experimental harness for test262

    tc39/test262-harness’s past year of commit activity
    JavaScript 94 BSD-3-Clause 49 14 7 Updated Mar 26, 2026
  • ecmarkup Public

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

    tc39/ecmarkup’s past year of commit activity
    TypeScript 238 MIT 74 101 13 Updated Mar 26, 2026
  • ecma262 Public

    Status, process, and documents for ECMA-262

    tc39/ecma262’s past year of commit activity
    HTML 15,609 1,405 355 (9 issues need help) 117 Updated Mar 26, 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) 4 Updated Mar 26, 2026
  • agendas Public

    TC39 meeting agendas

    tc39/agendas’s past year of commit activity
    JavaScript 1,171 201 0 3 Updated Mar 26, 2026
  • proposal-amount Public

    Numbers with precision and a unit for JavaScript

    tc39/proposal-amount’s past year of commit activity
    HTML 47 MIT 8 37 6 Updated Mar 26, 2026
  • proposal-error-capturestacktrace Public

    Standardizing Error.captureStackTrace

    tc39/proposal-error-capturestacktrace’s past year of commit activity
    12 MIT 4 5 0 Updated Mar 26, 2026
  • dataset Public

    The automatic track tc39 proposals

    tc39/dataset’s past year of commit activity
    TypeScript 47 Unlicense 11 2 0 Updated Mar 26, 2026
  • tc39/proposal-import-sync’s past year of commit activity
    63 MIT 2 7 1 Updated Mar 25, 2026
  • proposal-source-phase-imports Public

    Proposal to enable importing modules at the source phase

    tc39/proposal-source-phase-imports’s past year of commit activity
    HTML 159 MIT 11 6 0 Updated Mar 25, 2026