Publish subscribe mode

Publish subscribe mode

class EventEmitter {
  constructor() {
     this.cache = {}
  }
  
  //Registration events
  $on(eventType, fn) {
    //Add event
    this.cache[eventType] = this.cache[eventType] || [];
    this.cache[eventType].push(fn);
  }
  
  //Logout event
  $off(eventType) {
    if(this.cache[eventType]) {
        delete this.cache[name];
    }
  }
  
  //Trigger event
  $emit(eventType) {
    if(this.cache[eventType]) {
        this.cache[eventType].forEach(handle=>{
            handle();
        })
    }
  }
}

//Testing

let eventEmitter = new EventEmitter();
function f(){
   console.log("Jason");
}
eventEmitter.$on('click' f);
eventEmitter.$emit('click');        // Jason

EventEmitter. $off ('click '); // the click event logs off
EventEmitter. $emit ('click '); // click personal leave no longer exists