Stripe checkout.js - passing custom params to token callback

<script src="https://checkout.stripe.com/checkout.js"></script>
<button class='pay-deposit' data-booking-id='3455'>Pay Deposit</button>
<button class='pay-deposit' data-booking-id='335'>Pay Deposit</button>
<button class='pay-deposit' data-booking-id='34'>Pay Deposit</button> 

 # JS file
$('.pay-deposit').on('click', function(event) {
  event.preventDefault();

  // Get booking information from database
  var booking_id = $(this).data('booking-id');
  $.getJSON("/bookings/"+booking_id, function(data) {

    // Open Checkout with further options
    handler = stripe_checkout(booking_id);
    handler.open({
      name: "My Bookings",
      description: data["description"],
      amount: data["amount"],
      email: data["email"],
    });

    // Close Checkout on page navigation
    $(window).on('popstate', function() {
      handler.close();
    });
  });
});

function stripe_checkout(booking_id) {
  var handler = StripeCheckout.configure({
    key: 'pk_test_jPVRpCB1MLjWu2P71eTvXBZD',
    token: function(token) {
      // Send the charge through
      $.post("/charges/create", 
       { token: token.id, booking_id: booking_id }, function(data) {
        if (data["status"] == "ok") {
          window.location = "/some-url";
        } else {
          // Deal with error
          alert(data["message"]);
        }
      });
    }
  });
  return handler;
 }

# Bookings controller
class BookingsController < ApplicationController
  def show
    @booking = Booking.find(params[:id])
    attrs = @booking.attributes
    attrs.merge!("email" => current_user.email)

    respond_to do |format|
      format.json { render json: attrs.to_json }
    end
  end
end

# Charges controller
class ChargesController < ApplicationController

  def create
    booking = Booking.find(params[:booking_id])
    customer = Stripe::Customer.create(card: params[:token])

    charge = Stripe::Charge.create(
      customer:    customer.id,
      amount:      booking.amount,
      description: booking.description,
      currency:    'usd'
     )

    if charge.paid
      # Do some things for successful charge
      respond_to do |format|
        format.json { render json: {status: "ok"}.to_json }
      end
    else
      respond_to do |format|
        format.json { render json: {status: "fail", message: "Error with processing payment.  Please contact support."}.to_json }
      end
    end
  end
end