Introduction of Node.js Modules

In this article, we will see the introduction to Node.js Modules. Node.js modules provide a way to re-use code in your Node.js application. Node.js modules to be the same as JavaScript libraries. Node.js provide set of built-in modules which you can use without any further installation. like assert, crypto, fs, http, https, path, url, etc.

Please check more details or modules on Built-in Module in Node js.

Include Module in Node.js

for include module use the require() function with the name of the module.

var http = require('http');

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Now, your application has access to the HTTP module, and is able to create a server.

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/html'});
  res.end('Websolutionstuff !!');
}).listen(3000);

Create Custom Modules

You can create your custom modules and you can easily include in your applications.

In below example creates a module that returns a date and time object.

exports.custom_DateTime = function () {
  return Date();
};

Use the exports keyword to make properties and methods available outside the module file.

Save the code above in a file called "custom_module.js".

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Include Custom Modules

Now, you can include and use the module in any of your Node.js files.

var http = require('http');
var dt = require('./custom_module');

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/html'});
  res.write("Date and Time : " + dt.custom_DateTime());
  res.end();
}).listen(3000);

Notice that the module is located in the same folder as the Node.js file. or add path of module file.

Save above code in "custom_module_demo.js" file. and run below command in your terminal.

node custom_module_demo.js

Output :

Date and Time : Wed Sep 08 2021 20:05:04