Node(4) Module

Every javascript file in itself is a module

The require function searches for modules, and loads the module definition into the Node runtime

a module that defines a next function

//simple.jsvar count = 0;exports.next = function() { return count++; }

//to use simple.jsvar s = require( "./simple.js"); //.js can be omittednext();next();

any object/function assigned to exports are visible to the users. objects that not assigned to export are local to file.

./ means current directory

../ means the parent directory

You can include modules by finding modules in the node_modules directory

require( 'express' );

outputing funciton in module

function start() {  console.log("Request handler 'start' was called.");}function upload() {  console.log("Request handler 'upload' was called.");}exports.start = start;exports.upload = upload;

Searching for node_modules

node looks for modules in the current directory first and then keep move up to the parent folder until it finds the node_modules folder

require.paths

require.paths return the System-wide modules paths, but it is not necessary to set this env variable

to add a path to require.paths:

$ export NODE_PATH=/usr/lib/node
$ node
> require.paths;

but it is recommended to install modules in the node_modules folder.

npm

use npm to install package

-g flag installs package globally 

npm -g install packagename