JSQuestions/solutions/test-async-scheduler.js

const TaskScheduler = require('./async-scheduler');

function wait(ms, label, shouldReject = false) {
  return () => new Promise((resolve, reject) => {
    console.log(`${label} started`);
    setTimeout(() => {
      console.log(`${label} finished`);
      shouldReject ? reject(new Error(label + ' failed')) : resolve(label + ' ok');
    }, ms);
  });
}

(async () => {
  const scheduler = new TaskScheduler(2);

  // By default paused; add tasks
  const p1 = scheduler.addTask(wait(300, 't1'));
  const p2 = scheduler.addTask(wait(200, 't2'));
  const p3 = scheduler.addTask(wait(100, 't3'));
  const p4 = scheduler.addTask(wait(50, 't4'));

  console.log('Playing...');
  scheduler.play();

  try {
    const results = await Promise.all([p1, p2, p3, p4]);
    console.log('All results:', results);
  } catch (err) {
    console.error('One failed:', err.message);
  }
})();