CODE EXAMPLE FOR JAVASCRIPT

Invariant Violation: "main" has not been registered. This can happen if: * Metro (the local dev server) is run from the wrong folder. Check if Metro is running, stop it and restart it in the current project.

import { AppRegistry, Platform } from 'react-native';
import App from './App';

AppRegistry.registerComponent('X', () => App);

if (Platform.OS === 'web') {
    const rootTag = document.getElementById('root') || document.getElementById('X');
    AppRegistry.runApplication('X', { rootTag });
}