NodeJS Design Patterns (third edition) challenges

challenge-3-2.js

const { EventEmitter } = require('events');

const ticker = (num, cb) => {
  let timePassed = 0,
    count = 0;

  const emitter = new EventEmitter();

  const repeat = () => {
    if (timePassed >= num) return process.nextTick(() => cb(count));
    emitter.emit('tick', 'tock');
    setTimeout(repeat, 50);
    process.nextTick(() => (timePassed += 50));
    process.nextTick(() => (count += 1));
  };

  setTimeout(repeat, 50);

  return emitter;
};
const cb = completed => {
  console.log(`Completed ${completed} ticks`);
};

ticker(200, cb)
  .on('tick', tock => console.log(tock))
  .on('completed', x => console.log(x));