Examples from "JS 비동기 프로그래밍 이해하기[2]"

CountdownWithTimeout.js

class Countdown extends EventEmitter {
  constructor(seconds, superstitious) {
    super();
    this.seconds = seconds;
    this.superstitious = !!superstitious;
  }

  go() {
    const countdown = this;
    const timeoutIds = [];

    return new Promise((resolve, reject) => {
      for (let i = countdown.seconds; i >= 0; i--) {
        timeoutIds.push(setTimeout(() => {
          if(countdown.superstitious && i === 13) {
            timeoutIds.forEach(clearTimeout);
            return reject(new Error('OMG'));
          }
          countdown.emit('tick', i);
          if(i === 0) resolve();
        }, (countdown.seconds - i) * 1000));
      }
    });
  }
}