Documentation for npm run build

[ndao]

Googling around I find articles like these talking about using.env file when npm run build. However, I don't see any official documentation for that on this repo.

https://medium.com/@tacomanator/environments-with-create-react-app-7b645312c09d
https://serverless-stack.com/chapters/environments-in-create-react-app.html

So if I have 3 .env files: .env, .env.test, .env.production, what is the proper/official way to specify a .env file when npm run build?

[ashutoshrishi]

The documentation is here:

https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md#adding-development-environment-variables-in-env

This is part of the User Guide in create-react-app / react-scripts: https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md

[ndao]

@ashutoshrishi im not quite finding where it it's saying run npm build with .env.test file for example?

[iansu]

You don't specify the env file manually. The settings in .env are the base config that is used by all scripts. The build script automatically uses the .env.production to add/override any settings from the base config. The test scripts uses .env.test in a similar way.

If you are looking to build for multiple environments (like qa, staging, production, etc.) then the instructions in this PR might help: #4117

[Timer]

PR #4117 has been merged.