process.env.NODE_ENV 是否自动设置为“生产”？

Question

I was reading someone's code and came across this line.

if (process.env.NODE_ENV === 'production') { ...

This is a node.js application with express server and reactjs front end. So lets say we deploy it to heroku will it get this NODE_ENV variable automatically(or set by heroku itself) or do I have to set it manually as we set other env variables in development server?

Answer 1

如此处所述，如果您将 NODE_ENV 部署在 Heroku 上，则默认设置为生产： https ://devcenter.heroku.com/articles/nodejs-support#runtime-behavior

Answer 2

process.env refers to the environment variables on the system. This depends a whole lot on where the application runs and how the system is configured. Herocku does not know if a specific version of your app is in test or production. So the developer has defined an environment and added 'production' as a variable in that environment.

If you use npm you can add variables with script command

{
  ..
  "scripts": {
    "dev": "corss-env ENVIRONMENT=development ..",
    "prod": "cross-env ENVIRONMENT=production .."
  }
  ..
}

and use the appropriate command as run according to setting.

https://www.npmjs.com/package/cross-env

Answer 3

Inside in your project in Heroku, you can set all environments variables. Go in your project > settings > Config Vars and set NODE_ENV production.