J3Unit is an object-oriented unit testing framework for JavaScript. J3Unit runs JavaScript tests directly in the web browser and can be automated using JUnit and Jetty. J3Unit builds on previous work by JSUnit and Script.aculo.us to provide a better way to automate JavaScript unit tests. Object-oriented JavaScript unit tests are written using the Script.aculo.us Test.Unit.Runner object, which is in turn built upon the prototype JavaScript library.