JavaScript/callback.js at master · sill214/JavaScript · GitHub

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'use strict';

// Synchronous callback
functionprintImmediately(print){
print();
}

// Asynchrounous callback
functionprintWithDelay(print,timeout){
setTimeout(print,timeout);
}

// JavaScript is synchronous
// Execute the code block by orger after hoisting
// hoisting: var, function declaration
console.log('1');// 동기
setTimeout(()=>console.log('2'),1000);// 비동기
console.log('3');// 동기

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

printWithDelay(()=>console.log('Asynchrounous callback'),2000);// 비동기

// Callback Hell example
classUserStorage{
loginUser(id,password,onSuccess,onError){
setTimeout(()=>{
if(
(id==='sill'&&password==='dream')||
(id==='coder'&&password==='academy')
){
onSuccess(id);
}else{
onError(newError('not found'));
}
},2000);
}

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

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