// Create a client.
braintree.client.create({
  authorization: CLIENT_AUTHORIZATION
}, function (clientErr, clientInstance) {

  // Stop if there was a problem creating the client.
  // This could happen if there is a network error or if the authorization
  // is invalid.
  if (clientErr) {
    console.error('Error creating client:', clientErr);
    return;
  }

  // Create a PayPal Checkout component.
  braintree.paypalCheckout.create({
    client: clientInstance
  }, function (paypalCheckoutErr, paypalCheckoutInstance) {
    paypalCheckoutInstance.loadPayPalSDK({
      currency: 'USD',
      intent: 'capture'
    }, function () {
      paypal.Buttons({
        fundingSource: paypal.FUNDING.PAYPAL,

        createOrder: function () {
          return paypalCheckoutInstance.createPayment({
            flow: 'checkout', // Required
            amount: 10.00, // Required
            currency: 'USD', // Required, must match the currency passed in with loadPayPalSDK

            intent: 'capture', // Must match the intent passed in with loadPayPalSDK

            enableShippingAddress: true,
            shippingAddressEditable: false,
            shippingAddressOverride: {
              recipientName: 'Scruff McGruff',
              line1: '1234 Main St.',
              line2: 'Unit 1',
              city: 'Chicago',
              countryCode: 'US',
              postalCode: '60652',
              state: 'IL',
              phone: '123.456.7890'
            }
          });
        },

        onShippingChange: function (data, actions) {
          // Perform some validation or calculation logic on 'data'

          if ( /* need to update shipping options or lineItems */ ) {
            return paypalCheckoutInstance.updatePayment({
              amount: 10.00,              // Required
              currency: 'USD',
              lineItems: [...],           // Required
              paymentId: data.paymentId,  // Required
              shippingOptions: [...],     // Optional       
            });
          } else if (/* address not supported */) {
            return actions.reject();
          }

          return actions.resolve();
        },

        onApprove: function (data, actions) {
          return paypalCheckoutInstance.tokenizePayment(data, function (err, payload) {
            // Submit 'payload.nonce' to your server
          });
        },

        onCancel: function (data) {
          console.log('PayPal payment cancelled', JSON.stringify(data, 0, 2));
        },

        onError: function (err) {
          console.error('PayPal error', err);
        }
      }).render('#paypal-button').then(function () {
        // The PayPal button will be rendered in an html element with the ID
        // 'paypal-button'. This function will be called when the PayPal button
        // is set up and ready to be used
      });
    });
  });
});