spawn magic.js

import { spawn } from "child_process";
import * as readline from "readline";
const proc = spawn('node', ['/tmp/exec.js'], { stdio: 'pipe' });
const readInterface = readline.createInterface({ input: proc.stdout });
const readInterfaceStderr = readline.createInterface({ input: proc.stderr });
await new Promise((resolve, reject) => {
  readInterfaceStderr.on('line', (e: string) => {
    console.error(e);
    stderr += e + "\n";
  });
  readInterface.on('line', (e: string) => {
    console.log(e);
    stdout += e + "\n";
  });
  proc.on('exit', (code: number) => {
    code === 0 ? resolve(stdout): reject(new Error(stderr))
  });
});