charge.js

// load the stripe module pass in your secret token
// this will configure the `stripe` object for your
// account that you created earlier
const stripe = require('stripe')(process.env.STRIPE_SECRET);

// this function will charge the user's card,
// note that `req` is the http request, we'll
// see how to connect this all up later.
module.exports = (req) => {
  // the token is generated by Stripe and POST'ed
  // to the `action` URL in our form
  const token = req.body.stripeToken;

  // now we create a charge which returns a `promise`
  // so we need to make sure we correctly handle
  // success and failure, but that's outside of this
  // function (and we'll see it later)
  return stripe.charges.create({
    // ensures we send a number, and not a string
    amount: parseInt(process.env.STRIPE_COST, 10),
    currency: process.env.STRIPE_CCY,
    source: token,
    description: 'My Book', // 👈 remember to change this!
    // this metadata object property can hold any
    // extra private meta data (like IP address)
    metadata: {},
  });
}