Dummy Service in Python and its wrapper in JavaScript

dummy_service.py

import time
import pathlib
import random

time.sleep(random.randrange(1, 10, 1))
file = pathlib.Path('./finish')
file.touch()

SomeService.js

const { spawn } = require('child_process');
const fs = require('fs');
const fsPromises = fs.promises;

class SomeService {
  _proc;
  _callbacks;
  _intervals;

  constructor() {
    this._proc = null;
    this._callbacks = {};
    this._intervals = [];
  }

  _monitor() {
    const interval = setInterval(() => {
      fsPromises.access('finish')
      .then(() => {
        return fsPromises.unlink('finish')
          .then(() => {
            this._stopMonitor();
            if (this._callbacks.ready != null) {
              this._callbacks.ready();
              this._callbacks.ready = null;
            }
          });
      })
      .catch((err) => {
        console.log(err);
        console.log('Proc is not ready yet...');
      });
    }, 1 * 1000);
    this._intervals.push(interval);
  }

  _stopMonitor() {
    this._intervals.forEach((interval) => clearInterval(interval));
    this._intervals = [];
  }

  onReady(callback) {
    this._callbacks.ready = callback;
  }

  start() {
    this._monitor();
    this._proc = spawn('python3', ['dummy_service.py']);
  }

  stop() {
    this._proc.kill();
    this._stopMonitor();
  }
}

module.exports = SomeService;

startService.js

const SomeService = require('./SomeService');

const startService = (timeoutSec) => {
  const service = new SomeService();
  return new Promise((resolve, reject) => {
    service.onReady(() => {
      clearTimeout(onTimedout);
      resolve(service);
    });
    service.start();
    const onTimedout = setTimeout(() => {
      service.stop();
      reject(`Proc did not launch within ${timeoutSec} seconds.`);
    }, timeoutSec * 1000);
  });
};

startService(5)
.then(() => {
  console.log('Proc launched successfully.');
}, () => {
  console.log('Attempt to launch proc was timed out.');
});