Module Pattern JS

gistfile1.js

var UserPurchases = (function() {

  function UserPurchases(Q, UserSession, PurchaseModals) {
    this.Q = Q;
    this.UserSession = UserSession;
    this.PurchaseModals = PurchaseModals;    
  }

  UserPurchases.prototype.purchase = function(video) {
    this.video = video;
    return this.UserSession.signIn().then(this._promisePurchase(video));
  };

  UserPurchases.prototype.completePurchase = function(license) {
    this.user.addLicense(this.video, license);
    return this._purchaseDeferred.resolve(license);
  };

  UserPurchases.prototype._promisePurchase = function(video) {
    var _this = this;
    return function(user) {
      _this.user = user;
      _this._purchaseDeferred = _this.Q.defer();
      _this._resolveOrPrompt(video);
      return _this._purchaseDeferred.promise;
    };
  };

  UserPurchases.prototype._resolveOrPrompt = function(video) {
    if (this.user.owns(video)) {
      return this.completePurchase(this.user.licenseFor(video));
    } else {
      return this.PurchaseModals.openSaleForm(video);
    }
  };

  return UserPurchases;

})();