Difference between module.exports and exports in Node.js

module.exports is used when there is only a single item e.g., function, object or variable that needs to be exported, while exports is used for multiple items.

The module is a plain JavaScript Object representing the current module. It is local to each module and also it is private. It has exports property which is a plain JavaScript variable, set to module.exports. At the end of the file, Node.js return module.exports to the required function.

module.exports

When we want to export a single class/variable/function from one module to another module, we use module.exports.

Example: Create two files calculator.js and operation.js and export the Arithmetic class from calculator.js to operation.js using module.exports method. Here, we have created a class Arithmetic and exported the whole class using module.exports.

// Filename: calculator.js

class Arithmetic {
    constructor(a, b)
    {
        this.a = a;
        this.b = b;
    }

    add() { return this.a + this.b; }
    subtract() { return this.a - this.b; }

    multiply() { return this.a * this.b; }

    divide()
    {
        if (this.b != 0) {
            return this.a / this.b;
        }
        return "divided by zero !!!!";
    }
};

module.exports = Arithmetic;

// Filename: operation.js

const Arithmetic = require("./calculator.js");

const op = new Arithmetic(100, 40);

console.log(`Addition -> ${op.add()}`);
console.log(`subtraction -> ${op.subtract()}`);
console.log(`Multiplication -> ${op.multiply()}`);
console.log(`Division -> ${op.divide()}`);

Run the operation.js file using the following command:

node operation.js

Output:

exports

When we want to export multiple variables/functions from one module to another, we use exports.

Example: Create two files calculator.js and operation.js and export multiple functions from calculator.js file. 

// Filename: calculator.js

exports.add = (a, b) => a + b;
exports.subtract = (a, b) => a - b;
exports.multiply = (a, b) => a * b;
exports.divide = (a, b) => {
    if (b != 0) {
        return a / b;
    }
    return `Divided by zero !!!`;
}

// Filename: operation.js

const Arithmetic = require("./calculator.js");

console.log(`Addition -> ${Arithmetic.add(100, 40)}`);
console.log(
    `subtraction -> ${Arithmetic.subtract(100, 40)}`);
console.log(
    `Multiplication -> ${Arithmetic.multiply(100, 40)}`);
console.log(`Division -> ${Arithmetic.divide(100, 40)}`);

Run the operation.js file using the following command:

node operation.js

Output:

Difference between module.exports and exports 

Conslusion

In Node.js when we have only one item to export we can use module.exports but wehn there are muliple items we use exports property. The exports property also works for single item but module.exports don no work in case of multiple exports