What is a Module in Node.js?
A set of functions that you want to include in your application.
Built-in Modules
Node.js has a set of built-in modules that you can use without any further installation.
Examples:
assert | Provides a set of assertion tests |
buffer | To handle binary data |
child_process | To run a child process |
cluster | To spla singlit e Node process into multiple processes |
crypto | To handle OpenSSL cryptographic functions |
dgram | Provides implementation of UDP data gram sockets |
dns | To do DNS lookup and name resolution functions |
domain | Deprecated. To handle unhanded errors |
events | To handle events |
fs | To handle the file system |
http | To make Node.js act as an HTTP server |
https | To make Node.js act as an HTTPS server. |
net | To create servers and clients |
os | Provides information about the operation system |
path | To handle file paths |
punycode | Deprecated. A character encoding scheme |
querystring | To handle URL query strings |
readline | To handle readable streams one line at the time |
stream | To handle streaming data |
string_decoder | To decode buffer objects into strings |
timers | To execute a function after a given number of milliseconds |
tls | To implement TLS and SSL protocols |
tty | Provides classes used by a text terminal |
url | To parse URL strings |
util | To access utility functions |
v8 | To access information about V8 (the JavaScript engine) |
vm | To compile JavaScript code in a virtual machine |
zlib | To compress or decompress files |
How to Include Modules
To include a module, use the require()
function with the name of the module
Examples
var http = require(‘http‘);
var timers= require(‘timers‘);

Create Your Own Modules
You can create your own modules, and easily include them in your applications.
See the following example.
mydate.js
—————————————————————————————————
exports.myDateTime=function(){
return Date();
}
exports.myTime=function(){
var date=new Date();
return date.getHours()+”:”+date.getMinutes();
}
exports.myYear=function(){
var date=new Date();
return date.getFullYear();
}
exports.myMonth=function(){
var date=new Date();
return (date.getMonth()+1);
}
index.js
————————————————————————————————–
var http=require(‘http’);
var mydate=require(‘./mydate’);//here iclude my created module
http.createServer(
function (req,res){
var today=mydate.myDateTime();
res.write(“Today is:”+today+”\n”);
var now=mydate.myTime();
res.write(“Now time is:”+now+”\n”);
var year=mydate.myYear();
res.write(“Year is:”+year+”\n”);
var month=mydate.myMonth();
res.write(“Month is:”+month+”\n”);
res.end();
}
).listen(8080);


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

Thanks for another wonderful post. Where else could anyone get that type of info in such an ideal way of writing? I have a presentation next week, and I’m on the look for such information.