Node.js

• How to change value of process.env.PORT in node.js?
  https://stackoverflow.com/questions/13333221/how-to-change-value-of-process-env-port-in-node-js

在前端吃不到的變數：process.env.CUSTOMER_API_HOST，但可以用 webpack 打包進前端 code，否則需要在意是前端執行還是後端執行