meetup_event.js

class MeetupEvent {
  constructor(title, limit) {
    this.title = title;
    this.limit = limit
    this.attendees = [];
  } 

  register(member) {
    if (this.attendees.length < limit) {
      this.attendees.push(member);
    } else {
      throw new Error('ended');
    }
  }
}