I have a backend application made in nodeJS and express. The main app is divided into separate file, app.js and index.js. app.js is used for managing express, adding its controllers and connecting to MongoDB. index.js is there just for creating server.

Now I would like to implement service, that will check the current state in database, and in case of true, run some code, or function. And that code should be running all the time, regardless of sent requests. It should be a code for itself. So if anyone could tell me what is the best way of implementing this kind of behaviour.

Thank you!