How do you create a custom Node.js module?

Short answer: You can create a custom module by writing logic in a separate .js file and exporting it using module.exports.

Explain a bit more

📌 Example: mathUtils.js function add(a, b) { return a + b; module.exports = { add, subtract }; app.js const math = require('./mathUtils'); console.log(math.add(5, 3)); // 8 console.log(math.subtract(9, 4)); // 5 ✅ This is how you break your code into reusable pieces (modules) in Node.js. REST API Development in Node.js

Example code

} function subtract(a, b) { return a - b;
}

Real-world example (ShopNest)

A ShopNest BFF in Node.js aggregates catalog and price APIs for the React storefront.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.