utilities.js

function fin(promise, body) {
  return promise.then(function (res) {
    return as(body()).then(function() {
      return res;
    });
  }, function(function (err) {
    // if body throws something other, that will override current error
    return as(body()).then(function() {
      throw err;
    });
  });
}

// use like

fin(openStuff().then(asyncStuff), function(res) {
  return closeStuff();
})
.then(doOtherStuff);

from https://github.com/kriskowal/q

Promises also have a fin function that is like a finally clause. The final handler gets called, with no arguments, when the promise returned by getInputPromise() either returns a value or throws an error. The value returned or error thrown by getInputPromise() passes directly to outputPromise unless the final handler fails, and may be delayed if the final handler returns a promise.