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Upcoming meetings
  • DateNameLocation
  • 25 - 28 October 2021TC39 86th meetingVirtual meeting
  • 14 - 15 December 2021TC39 87th meetingVirtual meeting

TC39 has bi-monthly face to face meetings, usually on the West Coast but one meeting per year takes place in Europe. In addition, at least one meeting is held in Redmond, WA (July meeting usually). Attendance at meetings is controlled by Ecma International By-laws and Rules.

You can visit a TC39 panel video event which took place at the JSConf EU (JavaScript™ community in Europe) in 2018. The one which happened at the JSConf EU in 2017 is also available.

A presentation “ECMAScript® overview” by J. Neumann, former TC39 Chairman, is available. The audio file is available


ECMAScript® is the scripting language that is used to create web pages with dynamic behavior. ECMAScript®, which is also commonly known by the name JavaScript™, is an essential component of every web browser and the ECMAScript® standard is one of the core standards that enable the existence of interoperable web applications on the World Wide Web.

The ECMAScript® specification has been developed by Ecma TC39 whose membership includes all major browser vendors. The candidate milestone designates that the authoring process was completed, followed by a testing and validation phase of the project where TC39 members create and test implementations of the candidate specification to verify its correctness and the feasibility of creating interoperable implementations. The test implementations will also be used for web compatibility testing to ensure that the revised specification remains compatible with existing web applications. TC39 has committed to participating in this testing process. A test262 webpage is available.

Current work on ECMAScript®

Work on future ECMAScript® editions continues as part of the previously announced ECMAScript® “Harmony” project. A new Standard ECMA-414 “ECMAScript® Specification Suite” was adopted in June 2016. This International Standard defines the ECMAScript® Specification Suite containing the ECMAScript® programming language and its required and optional built-in libraries. ECMA-414 was forwarded to ISO/IEC JTC 1 for fast-track as ISO/IEC 22275.

The components of ECMAScript® are the following:

ECMA-402: “ECMAScript® 2018 Internationalization API Specification”
ECMA-404: “The JSON Data Interchange Syntax”
ECMA-414: “ECMAScript® Specification Suite”
ECMA TR/104: “ECMAScript® Test Suite”

Latest version of ECMAScript®

The ECMAScript®, Standard ECMA-262 11th edition is publicly available from the Ecma International website.

The latest drafts are available at: Reporters should generally only file bugs if the bug is still present in the latest drafts.

You are welcome to report feedback or issues via the GitHub issue tracker at:

If you have any information request, please kindly subscribe to the es-discuss mailing list.

Where to learn more about ECMAScript®

Please check this link to a JavaScriptTM/ECMAScript® tutorial.

ECMAScript® is a registered trademark of Ecma International.

JavaScriptTM is a trademark of Oracle.


Earlier versions of ECMAScript®

The ECMAScript®, Standard ECMA-262 Edition 6, Edition 7, Edition 8,  Edition 9, Edition 10 and Edition 11 were adopted respectively in June 2015, in June 2016, in June 2017, in June 2018, in June 2019 and in June 2020.

The ECMAScript®, Standard ECMA-262 Edition 5.1 (identical with ISO/IEC 16262 third Edition), is publicly available from the Ecma International web site. A comparable test suite known as Test262 (ES5) has been developed and approved as ECMA TR/104.

The revision of ECMA-262 known as ECMAScript®, fifth Edition was approved in December, 2009. It was previously developed under the working name ECMAScript® 3.1. The fifth Edition codifies de facto interpretations of the language specification that have become common among browser implementations and adds support for new features that have emerged since the publication of the third Edition. Such features include accessor properties, reflective creation and inspection of objects, program control of property attributes, additional array manipulation functions, support for the JSON object encoding format, and a strict mode that provides enhanced error checking and program security.

Testing of the fifth Edition was completed by mid-July 2009. Technical errors and ambiguities were resolved during this process, and a final draft of the specification was agreed upon in September for submission to the Ecma General Assembly for final approval in December 2009. This has resulted in a fast-track submission and ballot within ISO/IEC JTC 1 for revision of ISO/IEC 16262.

An earlier major revision of the ECMAScript® standard was the third Edition, published in 1999 (a Russian translation of ECMA-262 3rd edition is available). After completion of the third Edition, significant work was done to develop a fourth Edition. Although development of a fourth Edition was not completed, that work influenced ECMAScript®, fifth Edition and is continuing to influence the ongoing development of ECMAScript®.

ECMAScript® Development Archive

Ecma International hosts a publicly accessible collection of documents that record the activities of Ecma TC39 as it initially created and evolved the ECMAScript® Language Specification and related standards. It includes meeting records (both formal and informal), presentation decks, proposals, draft documents, and many other artifacts. The collection is organized by year and currently covers the period 1996-2015.

How to join the TC39 work

If you want to officially participate into the standardization activities regarding ECMAScript®, you shall first apply to become an Ecma member (see the membership info).

Once your membership request has been officially accepted by the General Assembly, you will have to follow the Ecma Royalty-Free (RF) Patent Policy option.

Finally you shall register to the TC39 RF Technical Committee (TC) (either the WORD registration form or the PDF registration form) and the process has been completed. A list of companies which have signed the registration form for a TC39 Royalty Free TC is available.

Visitors on a one-time basis are usually approved by the Secretary General and requests should be directed to him for approval. Such visitors are kindly invited to fill in the TC39 ECMAScript® RF Contributor form.

TC39 development process

Please find hereafter two links to get useful information about the standardization process of TC39: and

ECMAScript® is a registered trademark of Ecma International.

JavaScriptTM is a trademark of Oracle.