class EventEmitter {
constructor(){
this.listeners = []
}
on(eventName,func){
const callbacks = this.listen[eventName] || []
callbacks.push(func);
this.listeners[eventName]=callbacks
}
off(eventName,func){
}
emit(eventName,...args){
const callbacks = this.listens[eventName]
if(callbacks.length>0){
callbacks.forEach((callback)=>{
callback(...args)
})
}
}
}