ECMAScript is the scripting language that forms the basis of JavaScript. ECMAScript is standardized by the ECMA International standards organization in the ECMA-262 and ECMA-402 specifications. The following ECMAScript standards have been approved or are being worked on:

Name Links Release date Description
Current editions
ECMA-262 2017 (ES 8) Working draft, repository 2017 ECMAScript 2017 (8th Edition), currently work in progress.
ECMA-402 4.0 Working draft, repository 2017 ECMAScript Internationalization API 4.0, currently work in progress.
Obsolete/historical editions
ECMA-262 (ES 1) PDF June 1997 the original ECMAScript standard.
ECMA-262 (ES 2) PDF August 1998 the second revision of the ECMAScript standard; also ISO standard 16262.
ECMA-262 (ES 3) PDF December 1999 the third revision of the ECMAScript standard; corresponds to JavaScript 1.5.
See also the errata
ECMA-262 (ES 5) PDF December 2009 ECMAScript 5
See also the ES5 errata and ECMAScript 5 support in Mozilla
ECMA-357 PDF June 2004 ECMAScript for XML (E4X).
See also the E4X errata.
ECMA-357 Edition 2 PDF December 2005 ECMAScript for XML (E4X).
ECMA-262 (ES 5.1) PDF, HTML June 2011 This version is fully aligned with 3rd edition of the international standard ISO/IEC 16262:2011.
It includes ES5 errata fixes, no new features.
ECMA-402 1.0 PDF, HTML December 2012 ECMAScript Internationalization API 1.0.
ECMA-262 2015 (ES 6) PDF, HTML June 2015 ECMAScript 2015 (6th Edition).
ECMA-402 2.0 PDF June 2015 ECMAScript Internationalization API 2.0.
ECMA-262 2016 (ES 7) HTML June 2016 ECMAScript 2016 (7th Edition). Now feature frozen. To be ratified later this year (June).
ECMA-402 3.0 HTML June 2016 ECMAScript Internationalization API 3.0. To be ratified later this year (June).

See Wikipedia ECMAScript entry for more information on ECMAScript history.

You can participate in or just track the work on the next revisions of the ECMAScript Language Specification, code-named "Harmony", and the ECMAScript Internationalization API Specification via public wiki and the es-discuss mailing list linked from


  • SpiderMonkey - the JavaScript engine used in various Mozilla products, including Firefox;
  • Rhino - the JavaScript engine written in Java;
  • Tamarin - the ActionScript virtual machine (used in the Adobe® Flash® Player);
  • Other implementations (Wikipedia).

See also

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 Last updated by: fscholz,