oloo tries

FirebaseService.js

var FirebaseService =  {
  init: function(fb) {
    this.fb = fb;
  },
  pathRef: function(args) {
    for (var i = 0; i < args.length; i++) {
      if (angular.isArray(args[i])) {
        args[i] = this.pathRef(args[i]);
      }
      else if (typeof args[i] !== 'string') {
        throw new Error('Argument ' + i + ' to firebaseRef is not a string: ' + args[i]);
      }
    }
    return args.join('/');
  },
  ref: function() {
    var ref = this.fb;
    var args = Array.prototype.slice.call(arguments);
    if (args.length) {
      ref = ref.child(this.pathRef(args));
    }
    return ref;
  },
  once: function(ref, on) {
    return new Promise(function (resolve, reject) {
      ref.once(on || 'value', function (snap) {
        resolve(snap);
      }, function (err) {
        reject(err);
      });
    });
  }
}

module.exports = FirebaseService;

try1.js

var FirebaseService = require('./FirebaseService');

// maybe this way?
var ProfileService = Object.create(FirebaseService);
ProfileService.profileRef = function(id) {
  return this.ref("users").child(id).child("profile");
};
Profile.getProfile = function(id) {
  return this.once(this.getProfile(id), 'value');
};

var UserService = Object.create(FirebaseService);
UserService.usersRef = function(id) {
  return this.ref("users").child(id);
};
UserService.getUser = function(id) {
  return this.once(this.usersRef(id), 'value');
};

// what to export?
module.exports = {
  UserService: UserService,
  ProfileService: ProfileService,
  // ect.
};

try2.js

var FirebaseService = require('./FirebaseService');

var UserService = Object.create(FirebaseService);
UserService.usersRef = function(id) {
  return this.ref("users").child(id);
};
UserService.getUser = function(id) {
  return this.once(this.usersRef(id), 'value');
};

// or maybe this way?
var ProfileUserService = Object.create(UserService);
ProfileUserService.getProfile = function(id) {
  return this.once(this.usersRef(id).child("profile"), 'value');
};

// what to export?
module.exports = {
  UserService: UserService,
  ProfileUserService: ProfileUserService,
  // ect.
};

try3.js

var FullUserService = Object.create(UserService);
FullUserService.ProfileService = Object.create(ProfileService);
FullUserService.AnotherService = Object.create(AnotherService);

U.ProfileService.getProfile();
// U.getProfile()?

usage.js

var U = Object.create(ProfileUserService); // or just UserService
U.init(fb);
u.getUser("id").then(function(user) {
  console.log('found user')
});

u.getProfile("id").then(function(profile) {
  console.log('found profile')
});

//u.getSomethingElse("id").then(function(somethingelse) {
//  console.log('found somethingelse')
//});