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I've read the NodeJS documentation in regard to the event loop: https://nodejs.dev/learn/the-nodejs-event-loop

I understand that functions like an API call or setTimeout have their own threads that resolve them, but how is NodeJS then notified of that resolve to place a setTimeout callback in the message queue, or a promise callback back in the call stack?

Is Node checking its job queue after each function execution in the call stack?

I am using this example to make a POST API call to an API: https://nodejs.dev/making-http-requests-with-nodejs#perform-a-post-request. No issues there, it works well.

Next, I wanted to create a function that makes this API call by taking in dynamic connection parameters, headers and payload. Did that and I am able to return the response object from the function so I can detect the response.statusCode, response.statusMessage, etc. Here's my Node.js code:

Module Code

Say there is a HTTP GET callback defined as: