|ECMA-262 11th Edition||2020||ECMAScript 2020 Language Specification|
|ECMA-262 10th Edition||2019||ECMAScript 2019 Language Specification|
|ECMA-262 9th Edition||2018||ECMAScript 2018 Language Specification|
|ECMA-402 5th Edition||Working draft, repository||2018||ECMAScript 2018 Internationalization API Specification|
|ECMA-262||June 1997||ECMAScript: A general purpose, cross-platform programming language. This was the first version of the ECMAScript standard.|
|ECMA-262 2nd Edition||August 1998||ECMAScript Language Specification. This is the second revision of the ECMAScript standard; also ISO standard 16262.|
See also the errata
|ECMA-262 5th Edition||December 2009||ECMAScript Language Specification. This is the fifth revision of the ECMAScript standard.
See also the ES5 errata and ECMAScript 5 support in Mozilla
|ECMA-357||June 2004||ECMAScript for XML (E4X).
See also the E4X errata.
|ECMA-262 5.1 Edition||PDF, HTML||June 2011||This version is fully aligned with the third edition of the international standard ISO/IEC 16262:2011.
It includes ES5 errata fixes, no new features.
|ECMA-402 1st Edition||PDF, HTML||December 2012||ECMAScript Internationalization API Specification|
|ECMA-262 6th Edition||PDF, HTML||June 2015||ECMAScript 2015 Language Specification|
|ECMA-402 2nd Edition||June 2015||ECMAScript 2015 Internationalization API Specification|
|ECMA-262 7th Edition||HTML||June 2016||ECMAScript 2016 Language Specification|
|ECMA-402 3rd Edition||HTML||June 2016||ECMAScript 2016 Internationalization API Specification|
|ECMA-262 8th Edition||HTML||June 2017||ECMAScript 2017 Language Specification|
|ECMA-402 4th Edition||HTML||June 2017||ECMAScript 2017 Internationalization API Specification|
ES.Next is a dynamic name that refers to whatever the next version is at the time of writing. ES.Next features are more correctly called proposals, because, by definition, the specification has not been finalized yet.
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 ecmascript.org.
- Dmitry Soshnikov's analysis of ECMA-262 Edition 3 and 5