异步编程

Promise

// Promise基础
const promise = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve('success');
  }, 1000);
});

promise
  .then(result => console.log(result))
  .catch(error => console.error(error));

// Promise链式调用
fetchUserData()
  .then(user => fetchUserPosts(user.id))
  .then(posts => processPosts(posts))
  .catch(error => handleError(error));

Async/Await

// 基本使用
async function getData() {
  try {
    const user = await fetchUser();
    const posts = await fetchUserPosts(user.id);
    return posts;
  } catch (error) {
    console.error(error);
  }
}

// 并行处理
async function getMultipleData() {
  const [users, posts] = await Promise.all([
    fetchUsers(),
    fetchPosts()
  ]);
  return { users, posts };
}

异步迭代

// for await...of
async function* asyncGenerator() {
  yield await Promise.resolve(1);
  yield await Promise.resolve(2);
}

async function processItems() {
  for await (const item of asyncGenerator()) {
    console.log(item);
  }
}

错误处理

1. Promise错误处理
2. try/catch使用
3. 全局错误处理
4. 异步错误传播