Define and using Modules: node module export or import

The module in the node is a simple JavaScript library where we write some variable and functions. in this tutorial, I am going to discuss that how we can define the module and import the module in another module. All application logic encapsulated into modules. A module is a simple javascript file which may be imported into another js file. In this example, we will create a simple module named “mymodule” and import into another js file.

Example:

Step1: Create a new node project folder and package.json using npm init command.

npm init

Above command will ask some names and creates package.json file.





Step 2: Create a new module and add the following code into it.

exports.fname = "Yogesh";
exports.lname = "sharma";
exports.fullname = function(){
    return this.fname +" "+this.lname;
}

In the above code, we have written a public method and public variables which are accessible in another JS file or main file “index.js” due to exports keyword.

Step 3 : Create new file index.js and add the following code into that

var http = require('http');
var obj = require('./mymodule');
http.createServer(function (req, res) {
   res.writeHead(200, {'Content-Type': 'text/plain'});
   res.write(obj.fullname());
   res.end('Hello World\n');
   
}).listen(9000, '127.0.0.1');
console.log('Server running at http://127.0.0.1:9000/');

in this code, we have used require  function to import the custom module into the current file. Using require we have created an object of the custom module.





Step 4:  Run program and see output

node index.js

Output: