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QRG: await vs Promise.all: Awaiting Arrays of Promises

🧠 Quick Reference: Awaiting Arrays of Promises​

❗ Problem​

You called an async function that returns an array of promises and expected this to work:

const result = await myAsyncBatchFunction(); // ❌ Doesn't work as expected

But result is still an array of unresolved Promise objects.

✅ Fix​

Use Promise.all(...) to await the entire array:

const result = await Promise.all(myAsyncBatchFunction()); // ✅ Now resolved

🔍 Why?​

  • await unwraps one Promise
  • An array of promises is not a promise itself
  • Promise.all([...]) returns a single promise that resolves to an array of resolved values

🧪 Example​

async function fetchAll() {
  return [fetchUser(), fetchPosts()];
}

const result = await fetchAll(); // ❌ result is [Promise, Promise]
const resolved = await Promise.all(fetchAll()); // ✅ resolved is [user, posts]

💡 Rule of Thumb​

If you're awaiting something that returns multiple things, and they're async, wrap it in Promise.all() — even if it's from an async function.