@vinaymavi

Agenda

Node modules
1. Core
2. Local
3. Third-party
Module.exports vs exports

Modules

A module is a peace of code that can be imported in any file.

// Syntax

var <identifier> = require(<mobule_name>)

Module-Name

// module name


// Local Module

start with /,./,../ 


// other then local module 
only <module_name>

Core Modules

Core modules are modules that come with nodeJS binary.

// Core modules

var http = require('http');
var fs = require('fs');
var util = require('util');
var os = require('os');
var path = require('path');
var zlib = require('zlib');

..
..

Core Modules

preference of core modules is always high.

var http = require("http")

node_modules/
            | http

Local Modules

// Local modules need to be start with

/, ./, ../

// local modules can have following extension 

.js, .json, .node 

// node resolver always run in this order.

Local Modules

// First search for package.json
// with main entry

{
   "main":"main.js"
}

// if package.json file is not found 
// then default file name is 

index.js

third party module

third party modules are community driven modules and should not have same name as core module.

# Some third party packages.

* chalk
* expressjs
* babel
* webpack
* jest
* react
* jquery
..
..

module warpper

Before a module's code is executed, Node.js will wrap it with a function wrapper that looks like the following:

(function(exports, require, module, __filename, __dirname) {

    // Module code actually lives in here

});

module warpper

console.log("DIR = "+__dirname);
console.log("FILE NAME = "+__filename);
console.log("### require.main ###");
console.log(require.main);

module warpper

module.exports vs exports

@vinaymavi

Thank you.