Download Opera 12 Build 1065 Pre-Alpha with Perfect JavaScript 5.1 Compliance

For a while, after Google Chrome started picking up steam, JavaScript performance became the main battle grounds between browser makers. That has died down a bit, since all modern browsers are doing a lot better in this department and the performance numbers are more closely packed together.

But just as important as performance, perhaps more so, is compliance, ensuring that the way a browser interprets JavaScript code conforms with the standard, so that developers know what to expect when writing their apps.

Opera is now boasting that the latest experimental build, Opera 12 build 1065 (pre-alpha), runs an almost perfect score in the Test262 test suite, the official ECMAScript (JavaScript) conformance test.

"This build adds full support for the ECMAScript (JavaScript) 5.1 specification," Opera announced when launching the latest experimental build.

"At time of writing the test262 test suite is reporting one error from a total of 10927 tests on the Windows and Mac platforms. As a comparison, Opera 11.51 on Windows has 3865 failures," it boasted.

That's quite an improvement and, currently, Opera is the best performing browser in the test suite. That said, the tests are at this point still in development, some are invalid, and may be altered, added or removed at any time.

"Keep in mind that the test262 test suite is undergoing active development and far from complete. Even a perfect score in the current version of the test suite does not guarantee perfect ES 5.1 conformance," Opera warned.

However, as far as the current test suite is concerned, Opera performs splendidly and is the only browser to boast full compliance with the latest ECMAScript 5.1.

For comparison, the latest Google Chrome 15.0.874.12 dev fails 413 tests out of 10978, Internet Explorer 10 Preview 2 7 tests out of 10935, and Firefox 9 168 tests out of 10978.

Opera for Windows is available for download here.
Opera for Mac is available for download here.
Opera for Linux is available for download here.