Node.js Modules







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Node.js Modules



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What is a Module in Node.js?


Consider modules to be the same as JavaScript libraries.


A set of functions you want to include in your application.





Built-in Modules


Node.js has a set of built-in modules which you can use without any further
installation.


Look at our Built-in Modules Reference for a
complete list of modules.




Include Modules


To include a module, use the require()
function with the name of the module:





var http = require('http');



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('Hello World!');
}).listen(8080);





Create Your Own Modules


You can create your own modules, and easily include them in your applications.


The following example creates a module that returns a date and time object:



Example


Create a module that returns the current date and time:



exports.myDateTime = 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 "myfirstmodule.js"









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Include Your Own Module


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



Example


Use the module "myfirstmodule" in a Node.js file:



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

http.createServer(function (req, res) {
   
res.writeHead(200, {'Content-Type': 'text/html'});
   
res.write("The date and time are currently: " + dt.myDateTime());
   
res.end();
}).listen(8080);

Run example »

Notice that we use ./ to locate the module, that means that the
module is located in the same folder as the Node.js file.


Save the code above in a file called "demo_module.js", and initiate the file:



Initiate demo_module.js:



C:UsersYour Name>node demo_module.js


If you have followed the same steps on your computer, you will see the same result as the example: http://localhost:8080






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