App.js

import clients from './clients';

/**
 * Start command:
 * env REACT_NATIVE_APP_CLIENT=ge react-native start
 * Bundle Command
 * react-native bundle --reset-cache --bundle-output ./output.js --entry-file ./index.js
 **/

console.log(
  clients(
    PROCESS_ENV.REACT_NATIVE_APP_CLIENT
  )
);

/**
 * if REACT_NATIVE_APP_CLIENT == ge then console.log will output { clientName: 'ge' }
 * if REACT_NATIVE_APP_CLIENT == visa then console.log will output { clientName: 'visa' }
 **/

clients.js

import clients from './clientsdir/**/*';

export default function(client){
	return clients[client];
}

clientsdir_ge_ge.js

export default {
	clientName: 'ge'
};

clientsdir_visa_visa.js

export default {
	clientName: 'visa'
};

In the filename, underscores are actually directory separators.

This uses two bable plugins:

• The first plugin assigns PROCESS_ENV to environment variables that are passed to react-native, filtering out anything that doesn't start with REACT_NATIVE_APP.
• The second babel plugin will allow importing multiple files at once.