runPackager.ts

import {isPackagerRunning, logger} from '@react-native-community/cli-tools';
import {startServerInNewWindow} from './startServerInNewWindow';

export async function runPackager(
  port: number,
  root: string,
  reactNativePath: string,
  terminal?: string,
  packager?: boolean,
) {
  if (!packager) {
    return;
  }
  const result = await isPackagerRunning(port);
  if (result === 'running') {
    logger.info('JS server already running.');
  } else if (result === 'unrecognized') {
    logger.warn('JS server not recognized, continuing with build...');
  } else {
    // result == 'not_running'
    logger.info('Starting JS server...');

    try {
      startServerInNewWindow(port, root, reactNativePath, terminal);
    } catch (error) {
      if (error instanceof Error) {
        logger.warn(
          `Failed to automatically start the packager server. Please run "react-native start" manually. Error details: ${error.message}`,
        );
      }
    }
  }
}