This page is deprecated and all ES5Conform tests have been contributed to ECMA's test262 project.

Project Description

The goal of this project was to develop a test suite that could be used to determine how closely a JavaScript implementation conforms to the ECMAScript, 5th Edition Language Specification. We hope that the availability of a common conformance test suite will help browser implementers achieve a very high degree of interoperability for their ECMAScript 5 implementations.

What is ECMAScript 5

"ECMAScript" is the name under which the language more commonly known as "JavaScript" is standardized. Development of the ECMAScript standard is the responsibility of Technical Committee 39 (TC39) of Ecma International. The ECMAScript standard is officially known as ECMA-262. ECMAScript 5 (or just ES5) is short hand for the "ECMA-262, 5th Edition ECMAScript Language Specification" the official name of the standard.

ECMAScript 5 was approved as an offical Ecma standard by the the Ecma General Assembly on December 3, 2009. The ECMAScript 5 Specification (PDF) is available from the Ecma International web site.

Project Coordination and Participation

The coordinators of this project represent organizations that are members of ECMA and participants in TC39. This project is being carried out in cooperation with ECMA TC39 but the actual operation of this development project is not currently an official ECMA activity. It is possible this some or all of this test suite may be formally adopted by TC39 as a formal ECMA publication.

TC39 members and other with an active interest in test ECMAScript implementations are invited to participate by running tests, identify issues, contributing tests, or becoming active developers on this project. Path submissions are welcomed from everyone.


  • Microsoft contributed the original set of approximately 900 tests.


All files in this project are licensed using the New BSD license. See the license tab of this project for the actual license text.

Downloading and Running the Tests

Simply go to the Downloads tab, download the latest release, unzip it, and open runtests.html in the browser you want to test. If you want to run the tests in a non-browser environment you could contribute to this project by writing an appropriate test driver.

Test Organization and Conventions

The tests are arranged in a hierarchy that reflects the organization of the ECMAScript 5 Specification. The organization is explained here.

Last edited Aug 8, 2011 at 6:44 PM by dfugate, version 1


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