What is a Module in Node.js?

A module is a way of grouping related functions or data in one or more JavaScript files in Node. js. Modules can be used again in different parts of a Node. js application without affecting other modules or the global scope. Each module has its own environment, so it is isolated from other modules.

Node.js has a number of built-in modules which we can use without any further installation. Here are some of the built-in modules:

1. assert
2. buffer
3. child_process
4. crypto
5. domain
6. stream
7. path
8. os
9. http
10. https

You can find more modules here: https://nodejs.org/api/modules.html

How to include Modules?

To include a module in node.js file, we use the require() function with the name of the module:

var http = require('http');

After including a module, we can apply it in our application. This is an example of using the http module that we imported.

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/html'});
  res.end('Hello World!');
}).listen(8080);