Await In Loop (ARCH3030)

Key typescript.async.await-in-loop · Severity info · Category async

Awaiting inside a for/while loop body over an array serializes independent async operations that could run concurrently with Promise.all.

Incorrect

async function loadAll(ids: string[]): Promise<User[]> {
  const users: User[] = [];
  for (const id of ids) {
    users.push(await fetchUser(id)); // serial, slow
  }
  return users;
}

Correct

async function loadAll(ids: string[]): Promise<User[]> {
  return Promise.all(ids.map((id) => fetchUser(id)));
}

Fix

Run independent operations concurrently with Promise.all; await in a loop only when there is a genuine sequential dependency.