React Native DEV and PROD variables

How do I know if my React Native app is running in production or development? Is there some sort of way within JavaScript to tell? Is there a global that is passed in?

You can use the __DEV__ global variable in JavaScript to determine if you're using React Native packager or not. If you are running your app in the iOS Simulator or Android emulator __DEV__ will be set to true.

https://reactnative.dev/docs/javascript-environment

When the __DEV__ variable is set to true, it turns on a bunch of useful development warnings. For production, it is recommended to set __DEV__=false.

You can use the __DEV__ variable. By default if you run your app with npx react-native run-ios or npx react-native run-android, it will run in Debug mode and __DEV__ will be true. In release mode, __DEV__ will be false. You can use it this way:

const CLOUD_API_BASE_URL = __DEV__ ? 'https://api-dev.yourdomain.com' : 'https://api-prod.yourdomain.com';

You can run the app in Release mode with the terminal: react-native run-android --variant release #android react-native run-ios --configuration Release #ios

Or open the ios folder in XCode, choose Product > Scheme > Edit Schemes Select Run in the left menu. For Build Configuration, choose 'Release' and uncheck 'Debug executable'

In Android Studio, similarly, you can set the build variant to release