Ticker

index.mjs

// 3.2 Ticker: Write a function that accepts a number and a callback as the
// arguments. The function will return an EventEmitter that emits an event
// called tick every 50 milliseconds until the number of milliseconds is passed
// from the invocation of the function. The function will also call the callback
// when the number of milliseconds has passed, providing, as the result, the total
// count of tick events emitted. Hint: you can use setTimeout() to schedule
// another setTimeout() recursively.

import EventEmitter from 'events';

function ticker(number, cb) {
  let tickCount = 0;
  const eventEmitter = new EventEmitter();

  const timer = function (totalMs) {
    setTimeout(() => {
      eventEmitter.emit('tick');
      tickCount++;

      if (totalMs <= 0) {
        return cb(tickCount);
      }

      timer(totalMs - 50);
    }, 50);
  };

  timer(number);

  return eventEmitter;
}

ticker(300, (tickCount) => console.log(`Tick count: `, tickCount)).on('tick', () => console.log('A tick is passed'));