The Chromium folk have posted about JavaScript conformance as they release a test runner for Sputnik, that allows you to easily run the complete test suite from within your browser:

Sputnik touches all aspects of the JavaScript language defined in the 3rd edition of the ECMA-262 spec. In many ways it can be seen as a continuation of and a complement to existing browser conformance testing tools, such as the Acid3 test. While we are always focused on improving speed, Sputnik is not about testing how fast your browser executes JavaScript, but rather whether it does so correctly.

Since we released the Sputnik tests as an open source project, the most requested feature has been the ability to run the tests in a browser, and we are excited to launch that functionality today. The new test runner lets you run the tests from a single URL and quickly see the results in your browser. This makes it easier both for users to see how well their browser conforms to the JavaScript spec, as well as for browser makers to find bugs and incompatibilities.

You can also use Sputnik to compare browser conformance.

The dart board shows relative conformance based on the number of tests that hit or miss. Of course, in the real world, all tests are not equal. This has been an issue with Acid tests. The race to 100 is socially interesting, but if you miss a few core tests that could be worse than meeting 10 corner cases in SVG

Go to Source