npm install
npm start
/node app.js
(or specify port #; default 3000)- Answer will be sent over as response
{"invalid_customers":[{"id":2,"invalid_fields":["name"]},{"id":3,"invalid_fields":["newsletter"]},{"id":5,"invalid_fields":["name"]},{"id":6,"invalid_fields":["name","age"]},{"id":11,"invalid_fields":["name","email"]},{"id":15,"invalid_fields":["newsletter"]}]}
NOTE: Be sure that your version of node/nodejs has native Promise support.