Today I happened across jsTester, which describes itself as:
JsTester allows validation of javaScript code inside java. It provides a group of assert methods like JUnit’s Assert, it also supports the validations described in http://javascript.crockford.com/remedial.html, and the ability to use your own validations (unary & binary predicates).
Looks interesting, although I admit I have yet to try it out.
If you’re interested in TDD’ing Javascript code, you might want to have a look at the following website: http://www.wanted-master-software-developers.com. It’s an online game that challenges players to TDD a JavaScript function by incrementally passing a series of 13 tests. Also includes a simple TDD framework in JavaScript.