Creating Custom Node.js Modules

Introduction

Node.js is a powerful runtime environment that allows developers to create scalable and efficient applications. Modules are a fundamental part of Node.js, enabling code reuse and organization. In this lesson, we will learn how to create custom Node.js modules.

What are Modules?

Modules in Node.js are small JavaScript files that can be included in other files. They help in organizing code into manageable sections. Node.js has a built-in module system, and you can create your own modules to encapsulate functionality.

Creating Custom Modules

To create a custom Node.js module, follow these steps:

1. Create a new JavaScript file.
2. Define your functions or variables in that file.
3. Export them using module.exports.

Example:

// mathModule.js
function add(a, b) {
    return a + b;
}

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

module.exports = {
    add,
    subtract
};
                

In this example, we created a simple math module that exports two functions, add and subtract.

Exporting Modules

To use your custom module, you need to import it into another file using the require() function.

Example:

// main.js
const mathModule = require('./mathModule');

const sum = mathModule.add(5, 3);
const difference = mathModule.subtract(5, 3);

console.log('Sum:', sum);
console.log('Difference:', difference);
                

Here, we imported the mathModule and used its exported functions.

Best Practices

• Keep modules focused on a single responsibility.
• Name your module files clearly to indicate their purpose.
• Document your modules with comments for better readability.
• Use default exports for modules that export a single entity.

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