Testing business logic in Javascript

If you test server side and its a node. js based app then there is the option ofkyuri
+ Vowsjs. If not then you might be able to get what you want with plain old code comments, writing the tests in coffeescript
(Which is simpler syntax, but compiles to Javascript) and any decent JavaScript unit testing framework, especially if you're using a good JavaScript MVC Framework. If you're into BDD then Jasmine
Shocould be your first evaluation. Otherwise first check outmocha (my favorite) for node apps, qunit if using jquery heavily & DOH
Dojo. you'll also need to decide on the environment you want to run your client side tests in. ideally your business logic shocould be decoupled from the UI, but if it's not then js-test-driver is
A great tool for running tests in real browsers. If you don't need a full browser then try phantomjs, it's good and much faster.