(Netscape) and JScript (Microsoft). The language was invented by Brendan Eich at Netscape and first
appeared in that company's Navigator 2.0 browser. It has appeared in all subsequent browsers from Netscape
and in all browsers from Microsoft starting with Internet Explorer 3.0.
The development of this Standard started in November 1996. The first edition of this Ecma Standard was
adopted by the Ecma General Assembly of June 1997.
That Ecma Standard was submitted to ISO/IEC JTC 1 for adoption under the fast-track procedure, and
approved as international standard ISO/IEC 16262, in April 1998. The Ecma General Assembly of June 1998
approved the second edition of ECMA-262 to keep it fully aligned with ISO/IEC 16262. Changes between the
first and the second edition are editorial in nature.
The third edition of the Standard introduced powerful regular expressions, better string handling, new control
statements, try/catch exception handling, tighter definition of errors, formatting for numeric output and minor
changes in anticipation of forthcoming internationalisation facilities and future language growth. The third
edition of the ECMAScript standard was adopted by the Ecma General Assembly of December 1999 and
published as ISO/IEC 16262:2002 in June 2002.
Since publication of the third edition, ECMAScript has achieved massive adoption in conjunction with the
World Wide Web where it has become the programming language that is supported by essentially all web
browsers. Significant work was done to develop a fourth edition of ECMAScript. Although that work was not
completed and not published1
as the fourth edition of ECMAScript, it informs continuing evolution of the
language. The present fifth edition of ECMAScript (published as ECMA-262 5th
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.
ECMAScript is a vibrant language and the evolution of the language is not complete. Significant technical
enhancement will continue with future editions of this specification.
This Ecma Standard has been adopted by the General Assembly of December 2009.
1 Note: Please note that for ECMAScript Edition 4 the Ecma standard number "ECMA-262 Edition 4" was reserved but not
used in the Ecma publication process. Therefore "ECMA-262 Edition 4" as an Ecma International publication does not
© Ecma International 2009xi