Using Q, is this the best way to pass the results of two sequenced promises to the subsequent `then`/`spread` clause?

CombiningSequencedPromiseResultsWithQ.js

'use strict';

var Q = require('q');
var cmd = new require('commander').Command();
var client = new require('myAwesomeApi').Client();

var getUsername = function(done) {
  var username;
  cmd.prompt('Username: ', function(name) {
    if (!name) {
      done(new Error('You must provide a username!'));
    }
    else {
      done(null, username);
    }
  });
};

var getPassword = function(done) {
  cmd.password('Password: ', '*', function(pass) {
    if (!pass) {
      done(new Error('You must provide a password!'));
    }
    else {
      process.stdin.destroy();
      done(null, pass);
    }
  });
};

Q.napply(getUsername, null, []).then(function(username) {
  return Q.napply(getPassword, null, []).then(function(password) {
    return Q.resolve([username, password]);
  });
}).spread(function(username, password) {
  return Q.napply(client.login, client, [username, password]);
})

FWIW, using .fail(...).done(...); feels very unnatural to me as the done handler is receiving a resolved promise value from my previous then but the fail handler is in the middle of the two, creating a mentally diverted/disjoint flow. Recommendations to fix that?

Where do you normally put your fail handler? Or, do you instead use the done handler's rejection argument (2nd function)? Would the done handler's rejection function receive failures from any point in the promise chain like fail does? I'm guessing not.

No, fail shouldn't go before done; in that case: it does change the semantics.

.then(f1, r1, p1).fail(f2).end() should be replaced with .then(f1, r1, p1).fail(f2).done() or .then(f1, r2, p1).done(undefined, f2). I often cap with an empty .done(); I sometimes use .done(f) or sometimes .done(f, r).

Also: if you're writing only for Node you can use .catch instead of .fail (and .finally instead of .fin).

Cool, I'll go with catch (definitely prefer its obviously semantic name over fail) and an empty done. Thanks again!