Mistake - Making an async function sync

I recently migrated Firebase to the latest version in WebMaker app. As part of the migration the way database instance is retrieved changed from asynchronous to synchronous. Earlier, I had a function to get the db instance, like so:

let dbPromise; // a promise that gets defined somewhere
async function getDb() {
  return dbPromise; // resolved to a dbInstance
}

And then wherever I wanted to do some operation in the DB, this is how would use the above getDb function:

async function doSomethingWithDb() {
  const db = await getDb();
  return getDoc(doc(db, "colId/userId"));
}

Then I did the migration to latest Firebase which removed the async part in getting the db instance. So it was time to make a few things synchronous. To keep changes minimal, I made the getDb function return the dbInstance directly, instead of a promise:

async function getDb() {
  return dbInstance;
}

And since I wasn't returning any promise now, I could use the db without an await:

function doSomethingWithDb() {
  const db = getDb();
  return getDoc(doc(db, "colId/userId"));
}

But this didn't work! I got error from Firebase about wrong database instance being passed to it. But I was passing the same thing which I got from promise resolution earlier, being returned directly from getDb now. Oh wait...I spotted the mistake I made. It doesn't matter what you return from an async function, it always returns a promise. I had missed removing the async keyword from the getDb function and so it was still returning a promise. The fix was simple - changing the getDb to:

function getDb() {
  return dbInstance;
}

And that fixed it!

I’ll see you again with my next mistake! 👋🙂