220817(수)

  var copyDeep = function (target) {
  	var result = {};
  	if (typeof target === 'object' && target !== null) {
  		for (var prop in target) {
  			result[prop] = copyDeep(target[prop];
  			}
  		} else {
  			result = target;
  		}
  		return result;
  	};

// 1-0. setTimeout으로 비동기 제어(실패)
function findUser(id) {
  let user;
  setTimeout(function () {
    console.log("waited 0.1 sec.");
    user = {
      id: id,
      name: "User" + id,
      email: id + "@test.com",
    };
  }, 100);
  return user;
}

const user = findUser(1);
console.log("user:", user); // user: undefined

// 1-1. setTimeout으로 비동기 제어(성공)
function findUserAndCallBack(id, cb) {
  setTimeout(function () {
    console.log("waited 0.1 sec.");
    const user = {
      id: id,
      name: "User" + id,
      email: id + "@test.com",
    };
    cb(user);
  }, 100);
}

findUserAndCallBack(1, function (user) {
  console.log("user:", user);
});

// 1-2. Promise로 비동기 제어
findUser(1).then((user) => console.log('user:', user))
function findUser(id) {
	return new Promise((resolve, reject) => {
		setTimeout(function () {
    console.log("waited 0.1 sec.");
    const user = {
      id: id,
      name: "User" + id,
      email: id + "@test.com",
    };
    resolve(user)
  }, 100);

// 2-1. Promise로 비동기 제어
function fetchAuthorName(postId) {
  return fetch(`https://jsonplaceholder.typicode.com/posts/${postId}`)
    .then((response) => response.json())
    .then((post) => post.userId)
    .then((userId) => {
      return fetch(`https://jsonplaceholder.typicode.com/users/${userId}`)
        .then((response) => response.json())
        .then((user) => user.name);
    });
}

fetchAuthorName(1).then((name) => console.log("name:", name));

// 2-2. async/await로 비동기 제어
async function fetchAuthorName(postId) {
  const postResponse = await fetch(
    `https://jsonplaceholder.typicode.com/posts/${postId}`
  );
  const post = await postResponse.json();
  const userId = post.userId;
  const userResponse = await fetch(
    `https://jsonplaceholder.typicode.com/users/${userId}`
  );
  const user = await userResponse.json();
  return user.name;
}

fetchAuthorName(1).then((name) => console.log("name:", name));