1 Introduction

Microsoft web browsers support ECMAScript Language Specification [ECMA-262/51], Standard ECMA-262 5.1 Edition / June 2011, with the same variations listed in [MS-ES5] against an earlier specification, [ECMA-262/5] See [MS-ES5EX], Internet Explorer Extensions to the ECMA-262 ECMAScript Language Specification (Fifth Edition), for a list of extensions to the [ECMA-262/51] specification.

The supported specification is edition 5.1 of the standard for ECMAScript, a web page scripting language. ECMAScript is based on several originating technologies, the best known being JavaScript (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.