'use strict';

// Hint: you need Node.js >= v19.0.0

class Timer extends EventTarget {
  #counter = 0;

  constructor(delay) {
    super();
    setInterval(() => {
      const step = this.#counter++;
      const data = { detail: { step } };
      const event = new CustomEvent('step', data);
      this.dispatchEvent(event);
    }, delay);
  }
}

// Usage

const timer = new Timer(1000);

timer.addEventListener('step', (event) => {
  console.log({ event, detail: event.detail });
});