apple-pay-demo.js

var session
if (window.ApplePaySession) {
  var merchantIdentifier = 'merchant.com.canine-clothing'
  ApplePaySession.canMakePaymentsWithActiveCard(merchantIdentifier)
    .then(function (canMakePayments) {
      if (canMakePayments) {
          showApplePayButtons()
      }
    });
}

var paymentRequest = {
   currencyCode: 'USD',
   countryCode: 'US',
   total: {
      label: 'Canine Clothing',
      amount: '19.99'
   },
   supportedNetworks: ['amex', 'discover', 'masterCard', 'visa'],
   merchantCapabilities: ['supports3DS'],
   requiredShippingAddressFields: ['postalAddress']
};

$('.apple-pay-button').on('click', function () {
  session = new ApplePaySession(1, paymentRequest)
});