Map

오늘도 맵에 관해서 사투를 하고 있다.

https://www.youtube.com/watch?v=QOVV71EbgBA

mdn

https://developer.mozilla.org/ko/docs/Web/JavaScript/Reference/Global_Objects/Array/map

Tree.prototype.map = function(callback) {
  let tree = new Tree();
  tree.value = callback(this.value);

  if (this.children) {
    for (let el of this.children) {
      tree.children.push(el.map(callback));
    }
  }

  return tree;
};

근데 callback이 너무 어렵다

Callback

https://www.youtube.com/watch?v=j0Viy3v97gY

'use strict';

//Synchronous callback

function printImmediately(print) {
    print()
}

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


/// Asynchronous callback

function printWithDelay(print,timeout) {
    setTimeout(print, timeout);
}


console.log('1');
setTimeout( () =>console.log('2'),1000 )
console.log('3');
printImmediately(() => console.log('hello'));
printWithDelay(()=> console.log('async callback'),2000)

1 ​​​​​at ​callback.js:19:0​

3 ​​​​​at ​callback.js:21:0​

hello ​​​​​

2 ​​​​​

async callback ​​​​​

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

  getRoles(user, onSuccess, onError) {
      setTimeout(() => {
          if( user ===' ellie') {
              onSuccess({name:'ellie', role: 'admin'});
          } else {
              onError(new Error('no access'));
          }
      },1000)
  }
}


/// 1. id,password
/// 2. login
/// 3


const userStorage = new UserStorage();

const id = prompt('enter your id');
const password = prompt('enter your password');
userStroage.loginUser(
  id,
  password,
  user => {
    userStorage.getRoles(
      user,
      userWithRole => {
        alert(`Hello ${useWithRole.name}, you have a ${userWithRole.role} role`)
      },
      error => {
        console.log(error);
      }
    );
  },
  error => {
    console.log(error)
  }
);

이건 뭔소리냐