Bugs

JavaScript Async/Await Mistakes: What Goes Wrong

Missing await, sequential execution where parallel is possible, and unhandled rejections are extremely common in JavaScript async code.


❌ Sequential Instead of Parallel

async function loadDashboard(userId) {
  const user  = await fetchUser(userId);
  const posts = await fetchPosts(userId);  // Waits for user first
  const notifs = await fetchNotifications(userId);  // Waits for posts
  return { user, posts, notifs };
}

✅ Parallel with Promise.all

async function loadDashboard(userId) {
  const [user, posts, notifs] = await Promise.all([
    fetchUser(userId),
    fetchPosts(userId),
    fetchNotifications(userId)
  ]);
  return { user, posts, notifs };
}
💡

Pro tip: Use Promise.all() for independent async operations. Total time becomes the slowest single call instead of the sum of all calls.

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