JavaScript Unit Testing framework

 QUnit is a powerful, easy-to-use, JavaScript test suite. It's used by
 the jQuery project to test its code and plugins but is capable of
 testing any generic JavaScript code (and even capable of testing
 JavaScript code on the server-side).
 .
 QUnit is especially useful for regression testing: Whenever a bug is
 reported, write a test that asserts the existence of that particular
 bug. Then fix it and commit both. Every time you work on the code
 again, run the tests. If the bug comes up again - a regression - you'll
 spot it immediately and know how to fix it, because you know what code
 you just changed.
 .
 Having good unit test coverage makes safe refactoring easy and cheap.
 You can run the tests after each small refactoring step and always know
 what change broke something.
 .
 QUnit is similar to other unit testing frameworks like JUnit, but makes
 use of the features JavaScript provides and helps with testing code in
 the browser, e.g. with its stop/start facilities for testing
 asynchronous code.