app.js

var shopify = new shopifyAPI({
  shop: 'kauai-project.myshopify.com', // MYSHOP.myshopify.com
  shopify_api_key: 'xxxxxxxx', // Your API key
  shopify_shared_secret: 'xxxxxxxxxx', // Your Shared Secret
  shopify_scope: 'read_orders, write_orders, read_customers, write_customers, read_products',
  redirect_uri: 'http://localhost:3000/dashboard',
});

async function send_to_shopify(billing_data) {
  console.log(billing_data)
  shopify.customer.create({
    email: billing_data['email'],
    first_name: billing_data['first_name'],
    last_name: billing_data['last_name'],
    addresses: [
      {
        address1: billing_data['address'],
        address2: billing_data['addressTwo'],
        city: billing_data['city'],
        province: billing_data['state'],
        zip: billing_data['zip']
      }
    ]
  });
}