callback

'use strict';
    //JavaScript is synchronous.

    //hoisting: var, funciton declaration

console.log('1');
setTimeout(()=>console.log('2'), 1000);
console.log('3');

 
// Synchronous callback 즉각적으로 동기적으로 실행
function printImmediately(print){
	print();
}

printImmediately(() => console.log('hello'));

// Asynchronous callback 언제 실행될지 모름
function printwithDelay(print, timeout){
	setTimeout(print, timeout);
}

printwithDelay(()=> console.log('async callbak'), 2000);

//javascript는 함수를 인자로 호출할수 있음

// Callback Hell example
class UserStorage{
	loginUser(id, password, onSuccess, onError){
		setTimeout(() => {
			if(
				(id === 'ellie' && password === 'dream') ||
				(id === 'coder' && password === 'academy') 
			){
				onSuccess(id);
			} else {
				onError(new Error('not fount'));
			}
			
		}, 2000);
	}

	getRoles(user, onSuccess, onError) {

	}
	set
}