Jules Ivanic Jules Ivanic - 5 months ago 70
Javascript Question

React-native : detect dev or production env

I develop a react-native app where some API calls should be made.

If I'm in production mode my app should call, for example, this host :

https://example.com/


but if I'm in dev mode, it should call my local host machine on a different port, for example :

http://192.168.0.10:8080/


How the react-native code can be aware of its environment ?

.dotenv
seems to not work with react-native.

In the Chrome debug, we can see that the application is launched with some params :

Running application "AppName" with appParams: {"initialProps":{},"rootTag":1}. __DEV__ === true, development-level warning are ON, performance optimizations are OFF


Can we get this
__DEV__
value in the application ?

Thanks

Answer

Set automatically

The constant __DEV__ is set automatically.

Production

Building the bundle via --dev=false should unset __DEV__.

Usage

if (__DEV__) {
    console.log('Development');
} else {
    console.log('Production');
}
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