Node.js Basics - Modules and npm

Node.js allows developers to modularize their code using modules and manage project dependencies using npm (Node Package Manager). Understanding modules and npm is essential for building scalable and maintainable Node.js applications.

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1. Modules in Node.js

Modules in Node.js are encapsulated units of functionality that can be reused across different parts of an application. Each module typically represents a single JavaScript file and can export functions, objects, or variables for use in other modules.

Example of creating and using a module:

// math.js - Example module
const add = (a, b) => {
    return a + b;
};

const subtract = (a, b) => {
    return a - b;
};

module.exports = { add, subtract };

// app.js - Main application file
const math = require('./math');

console.log(math.add(5, 3)); // Output: 8
console.log(math.subtract(5, 3)); // Output: 2

In the above example, math.js exports two functions (add and subtract), which are then imported and used in app.js.

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2. npm (Node Package Manager)

npm is the default package manager for Node.js, allowing developers to install, manage, and publish packages or modules for Node.js applications. npm provides access to a vast ecosystem of open-source libraries and tools that can be easily integrated into Node.js projects.

Example of using npm to install a package:

$ npm install lodash

This command installs the lodash package from the npm registry and adds it to the dependencies section of the package.json file.

Once installed, you can import and use the package in your Node.js application:

// app.js - Main application file
const _ = require('lodash');

const numbers = [1, 2, 3, 4, 5];
const sum = _.sum(numbers);

console.log(sum); // Output: 15

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3. Conclusion

Understanding modules and npm is fundamental for building Node.js applications. By modularizing code into reusable modules and leveraging npm to manage project dependencies, developers can streamline development, enhance code maintainability, and leverage the rich ecosystem of open-source packages available for Node.js.