module.exports vs exports

1. Definition

In Node.js, both module.exports and exports are used to export data from a module so it can be used in other files. However, they work slightly differently under the hood.

2. module.exports

Main object that is returned when require() is called
Can export a function, object, or value
Used when exporting a single value

3. exports

Shorthand reference to module.exports
Used to add multiple properties
Cannot directly assign a new value

4. Key Differences

Usage: module.exports → single export | exports → multiple exports
Assignment: module.exports can be reassigned | exports cannot
Reference: exports is a reference to module.exports

5. Example

👉 Using module.exports

// math.js
module.exports = function add(a, b) {
  return a + b;
};

// app.js
const add = require("./math");
console.log(add(2, 3));

👉 Using exports

// math.js
exports.add = (a, b) => a + b;
exports.sub = (a, b) => a - b;

// app.js
const math = require("./math");
console.log(math.add(2, 3));

6. Important Note

If you assign a new value to exports, it will break the reference with module.exports and will not work as expected.

// ❌ Wrong
exports = function() {};

// ✅ Correct
module.exports = function() {};

7. Advantages

Helps in modular code structure
Supports code reuse
Makes large applications manageable