How to create an event for the appearance of a file (picture) in a folder in node js?

Question

JavaScript

Several virtual machines in each of them. An app.js file that saves the picture in a public place. And over time, this folder is filled with new files (pictures). And actually on the main machine, the app.js file that monitors this folder and says "Oops, we have a new file." Of course, I can create a function that will run after the nth amount of time, but perhaps there are other options?