Discussion on: MongoDB Atlas Hackathon Help Thread

What I meant by MongoClient instance is the one which I used to query my Atlas database and collections.

Yes, you can use the realm-web package for this. To call a serverless function called sum with the arguments 2 and 3, you would use the following code:

const functionName = "sum";
const args = [2, 3];
const result = await user.callFunction(functionName, args);

You can find out more about how to use Realm functions in the documentation.