app/static/googlePay.js

// Copyright 2018 Google LLC.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Script for configuring Google Pay.
// See https://developers.google.com/pay/api/web/guides/setup for more information.

const baseRequest = {
  apiVersion: 2,
  apiVersionMinor: 0
};
const allowedCardNetworks = ['AMEX', 'DISCOVER', 'JCB', 'MASTERCARD', 'VISA'];
const allowedCardAuthMethods = ['PAN_ONLY', 'CRYPTOGRAM_3DS'];

const tokenizationSpecification = {
  type: 'PAYMENT_GATEWAY',
  parameters: {
    'gateway': 'example',
    'gatewayMerchantId': 'exampleGatewayMerchantId'
  }
};

const baseCardPaymentMethod = {
  type: 'CARD',
  parameters: {
    allowedAuthMethods: allowedCardAuthMethods,
    allowedCardNetworks: allowedCardNetworks
  }
};

const cardPaymentMethod = Object.assign(
  {},
  baseCardPaymentMethod,
  {
    tokenizationSpecification: tokenizationSpecification
  }
);

let paymentsClient = null;

function getGoogleIsReadyToPayRequest () {
  return Object.assign(
    {},
    baseRequest,
    {
      allowedPaymentMethods: [baseCardPaymentMethod]
    }
  );
}

function getGooglePaymentDataRequest () {
  const paymentDataRequest = Object.assign({}, baseRequest);
  paymentDataRequest.allowedPaymentMethods = [cardPaymentMethod];
  paymentDataRequest.transactionInfo = getGoogleTransactionInfo();
  paymentDataRequest.merchantInfo = {
    merchantName: 'Example Merchant'
  };
  return paymentDataRequest;
}

function getGooglePaymentsClient () {
  if (paymentsClient === null) {
    paymentsClient = new google.payments.api.PaymentsClient({environment: 'TEST'});
  }
  return paymentsClient;
}

function onGooglePayLoaded () {
  const paymentsClient = getGooglePaymentsClient();
  paymentsClient.isReadyToPay(getGoogleIsReadyToPayRequest())
    .then(function (response) {
      if (response.result) {
        addGooglePayButton();
      }
    })
    .catch(function (err) {
      console.error(err);
    });
}

function addGooglePayButton () {
  const paymentsClient = getGooglePaymentsClient();
  const button =
    paymentsClient.createButton({onClick: onGooglePaymentButtonClicked});
  document.getElementById('google-pay').appendChild(button);
}

function getGoogleTransactionInfo () {
  return {
    currencyCode: 'USD',
    totalPriceStatus: 'FINAL',
    totalPrice: '1.00'
  };
}

function prefetchGooglePaymentData () {
  const paymentDataRequest = getGooglePaymentDataRequest();
  paymentDataRequest.transactionInfo = {
    totalPriceStatus: 'NOT_CURRENTLY_KNOWN',
    currencyCode: 'USD'
  };
  const paymentsClient = getGooglePaymentsClient();
  paymentsClient.prefetchPaymentData(paymentDataRequest);
}

function onGooglePaymentButtonClicked () {
  const paymentDataRequest = getGooglePaymentDataRequest();
  paymentDataRequest.transactionInfo = getGoogleTransactionInfo();

  const paymentsClient = getGooglePaymentsClient();
  paymentsClient.loadPaymentData(paymentDataRequest)
    .then(function (paymentData) {
      processPayment(paymentData);
    })
    .catch(function (err) {
      console.error(err);
    });
}

function processPayment (paymentData) {
  console.log(paymentData);
}