1.8 Versions of JavaScript

Netscape has defined a number of versions of JavaScript. Microsoft has released more-or-less compatible versions under the name "JScript," and the ECMA standards body has released three versions of a JavaScript standard named "ECMAScript". The following paragraphs describe these various versions, and explain how they relate to each other. Each entry in the reference section contains availability information that documents the version of JavaScript in which a feature was introduced.

JavaScript 1.0

The original version of the language. It was buggy and is now essentially obsolete. Implemented by Netscape 2.

JavaScript 1.1

Introduced a true Array object; most serious bugs resolved. Implemented by Netscape 3.

JavaScript 1.2

Introduced the switch statement, regular expressions, and a number of other features. Almost compliant with ECMA v1, but has some incompatibilities. Implemented by Netscape 4.

JavaScript 1.3

Fixed incompatibilities of JavaScript 1.2. Compliant with ECMA v1. Implemented by Netscape 4.5.

JavaScript 1.4

Only implemented in Netscape server products.

JavaScript 1.5

Introduced exception handling. Compliant with ECMA v3. Implemented by Mozilla and Netscape 6.

JScript 1.0

Roughly equivalent to JavaScript 1.0. Implemented by early releases of IE 3.

JScript 2.0

Roughly equivalent to JavaScript 1.1. Implemented by later releases of IE 3.

JScript 3.0

Roughly equivalent to JavaScript 1.3. Compliant with ECMA v1. Implemented by IE 4.

JScript 4.0

Not implemented by any web browser.

JScript 5.0

Supported exception handling; partial ECMA v3 compliance. Implemented by IE 5.

JScript 5.5

Roughly equivalent to JavaScript 1.5. Fully compliant with ECMA v3. Implemented by IE 5.5 and IE 6.

ECMA v1

The first standard version of the language. Standardized the basic features of JavaScript 1.1 and added a few new features. Did not standardize the switch statement or regular expression support. Conformant implementations are JavaScript 1.3 and JScript 3.0.

ECMA v2

A maintenance release of the standard that included clarifications but defined no new features.

ECMA v3

Standardized the switch statement, regular expressions, and exception handling. Conformant implementations are JavaScript 1.5 and JScript 5.5.