Our final Serverless function for creating checkouts

handler.js

const SquareConnect = require('square-connect');
const crypto = require('crypto');
const querystring = require('querystring');

module.exports.checkout = (event, context, callback) => {
  (SquareConnect.ApiClient.instance).authentications["oauth2"].accessToken = process.env.ACCESS_TOKEN;
  const formData = querystring.parse(event.body);
  const locationId = process.env.LOCATION_ID;
  const checkoutRequest = {
    idempotency_key: crypto.randomBytes(48).toString('base64'),
    order: {
      idempotency_key: crypto.randomBytes(48).toString('base64'),
      reference_id: Date.now().toString(),
      line_items: [
          {
            catalog_object_id: formData.itemVarID,
            quantity: "1"
          }
      ]
    },
    merchant_support_email: "[email protected]"
  };
  const checkoutApi = new SquareConnect.CheckoutApi();

  checkoutApi.createCheckout(locationId, checkoutRequest).then((checkoutResponse)=>{
    const response = {
      statusCode: 302,
      headers: { Location: `${checkoutResponse.checkout.checkout_page_url}` }
    };
    callback(null, response);
  }).catch(error => {
      console.log(JSON.stringify(error, null, 2));
      callback(error)
  });
};