2694. Event Emitter

https://leetcode.com/problems/event-emitter/

Javascript

class EventEmitter {
  subscribed = {}

  subscribe(event, cb) {
    if (!this.subscribed.hasOwnProperty(event)) {
        this.subscribed[event] = []
    }
    this.subscribed[event].push(cb)
    
    return {
        unsubscribe: () => {
            if (this.subscribed[event] && this.subscribed[event].length > 1) {
                this.subscribed[event].pop()
            } else {
                delete this.subscribed[event]
            }
        }
    };
  }

  emit(event, args = []) {
      if (this.subscribed.hasOwnProperty(event)) {
          return this.subscribed[event].map(callback => callback(...args))
      }
      return []
  }
}