gistfile1.js

var q = require('q');

function jednaDroga(p) {
  //....
  p.resolve(wartosc);
  //....
}

function drugaDroga(p) {
  //....
  p.resolve(123);
  //....
}

function zdecyduj() {
  var deferred = q.defer();
  
  if(cokolwiek) jednaDroga(deferred);
  else drugaDroga(deferred);
  
  return deferred.promise;
}

zdecyduj()
  .then(function(wynik) {
  
  //whatever
  
  })
  .then(function(){
    // etc.
  })
  .done();