ticker.fix.mjs

import { EventEmitter } from 'events';

/**
 * @param {number} number 
 * @param {(n:number)=>any} callback 
 */
function ticker(
  number,
  callback
) {
  const emitter = new EventEmitter();
  let tick_count = 0;

  let ticker50 = () => {
    if (ticker50 !== null) {
      process.nextTick(() => {
        const t = new Date();
        if (t % 5 === 0) {
          emitter.emit('error', new Error('tick error'));
        } else {
          emitter.emit('tick', t);
          tick_count++;
        }
      });
      setTimeout(ticker50, 50);
    }
  };

  setTimeout(() => {
    ticker50 = null;
    callback(tick_count);
  }, number);

  ticker50();

  return emitter;
};

const runningTicker = ticker(1000, (tick_count) => {
  console.log(tick_count);
});

runningTicker
.on('tick', (t) => console.log(t))
.on('error', (err) => console.error(err.message));