I'm curious why they didn't build on the "wd" implementation of the WebDriver protocol for Node.js: https://github.com/admc/wd

Personally I like just using "wd" along with a promise helper library or two.

Here's an example using q-proxy (https://npmjs.org/package/q-proxy) and q-step (https://npmjs.org/package/q-step). The result is a pretty nice syntax (admittedly nicer in CoffeeScript than JavaScript) and a lot more flexibility to do other logic:

    browser = QProxy(wd.promiseRemote("localhost", 4444))
    QStep(
      -> browser.init(browserName: "firefox")
      -> browser.get("https://www.facebook.com/")
      -> browser.elementById("email").type(credentials.email)
      -> browser.elementById("pass").type(credentials.password)
      -> browser.elementById("u_0_b").click()
    )

Or wd's own built-in promise chaining is pretty similar to Nightwatch.js as well:

  browser
    .init({browserName:'chrome'})
    .get("http://admc.io/wd/test-pages/guinea-pig.html")
    .title()
      .should.become('WD Tests')
    .elementById('i am a link')
    .click()
    .eval("window.location.href")
      .should.eventually.include('guinea-pig2')
    .back()
    .elementByCss('#comments').type('Bonjour!')
    .getValue().should.become('Bonjour!')
    .fin(function() { return browser.quit(); })
    .done();