For the sake of the question lets assume I already have something that sends data to Lambda from an external source. My problem is working with that data so I can do any computations on it that I need to, then pass said data to another API in the form of a POST.

I'm new to lambda, so I am assuming I can create a REST like function using Node.js in Lambda. However I am not sure how that works. I have attempted to take the very minimal basic example they give you when creating a script but my returned response is some base encoded string or an array of numbers. So, thats not the expected result.