Resolving promise externally

resolve-externally.js

async function showRationaleDialog(title: string, message: string) {
  let done;
  const result = new Promise(resolve => {
    done = resolve;
  });

  const alert = Alert.alert(title, message, [
    {
      text: 'OK',
      onPress: () => done()
    }
  ]);

  return result;
}

Essentially hoists the resolve function outside the promise creation block, then calls it when ready.