0_donations.js

if (typeof window.EDH === 'undefined') {
  window.EDH = {};
}

if (typeof window.EDH.Donation === 'undefined') {
  window.EDH.Donation = {};
}

var Donation = window.EDH.Donation;

jQuery(function($) {
  braintree.onSubmitEncryptForm($form, function(event) {
    disableSubmitButton(true);
    event.preventDefault();

    Donation.MakePayment.make($form.serialize())
      .done(function(status) {
        window.location = status.thankYouURL;
      })
      .fail(function(status) {
        // update form
      });
  });
});

1_make_payment.js

(function() {
  var Payment = window.EDH.Donation.Payment,
      Poll    = window.EDH.Donation.Poll;

  var MakePayment = {
    make: function(props) {
      var payment = new Payment(props),
          poll    = new Poll();

      payment.save()
        .done(function() {
          return poll.ready(payment.getPollURL());
        });
    }
  };
})();

MakePayment.make();

2_payment.js

(function() {
  var Payment = function(props) {
    this.props = {};
    this.props.url = '<%= asset_url %>';

    var prop;
    for (prop in props) {
      this.props = [prop] = props[prop];
    }

    return this;
  };

  Payment.prototype.save = function() {
    var deferred = new $.Deferred();

    var _this = this;
    $.post(this.getURL(), this.props, {dataType: 'json'})
      .done(function(data) {
        _this.props = data;

        deferred.resolve({thankYouURL: _this.props.thank_you_url});
      });

    return deferred;
  };

  Payment.prototype.getURL = function() {
    var retry_order_url = this.props.retry_order_url;
    if (retry_order_url) {
      return retry_order_url;
    } else {
      return this.url;
    }
  };

  Payment.prototype.getPollURL = function() {
    return this.props.poll_url;
  };

  window.EDH.Payment = Payment;
})();

3_poll.js

(function() {
  var Poll = function(props) {
  };

  Poll.prototype.ready = function(url) {
    var deferred = new $.Deferred();

    $.get(url, 'json')
      .done(function(data) {
        if (data.state === 'payment_successful') {
          deferred.resolve();
        } else {
          deferred.reject();
        }
      })
      .fail(function() {
        // TODO
      });

    return deferred;
  };
});