How to update a JSON file using NodeJs? The data I want to post to the file is in my jquery program logic

How can I update my JSON file (can be found in the same local server as app.js containing all my program logic) using NodeJS? Should I put all of my program logic within nodeJS instead of having it in an external js file? If that's not necessary, how can I tell NodeJS to take data from my program logic and update the json file using NodeJS?

Any help will be appreciated

via Lean Junio