Cucumber.js is the Node.js library for Cucumber. You can use it with Selenium via LearnBoost's soda npm, and if you're building apps with SocketStream, there is an npm module to help you do BDD with SocketStream.
A lingering issue was that the selenium browser windows would not close after a cucumber.js feature was finished, leading to a large number of Google chrome windows being left open. To fix that issue in ss-cucumber, insert this cucumber.js step definition into your step_definitions file:
# This will close the selenium browser at the end of the cucumber feature @After (callback) -> wrap @browser.chain.testComplete(), callback