Sequential vs Parallel Await

The UI, test, redirect, or log moves forward before the async result is actually ready. Sequential awaits are correct for dependencies but slow for independent API calls.

Accidentally serializing independent work.

Await real dependencies, start independent work together, and choose the loop pattern that matches the behavior you need.

const [user, posts] = await Promise.all([
  fetchUser(),
  fetchPosts()
]);

The console lane proves the visible order: done. The active line and queues show why source order changed.

Measure before and after with logs or test spies: the dependent line should run only after the awaited operation finishes.