Using npm

Using NPM – the Package Manager for Node.js packages

View module version

d:\xampp\htdocs\pv\WRApp\test> npm view  selenium-webdriver versions

[ '2.1.0',
  '4.0.0-alpha  '2.33.2',
  '2.34.1' ].1' ]

D:\xampp\htdocs\pvdata\testSelenium\test> npm view  mocha@4.* version
mocha@4.0.0 '4.0.0'
mocha@4.0.1 '4.0.1'
mocha@4.1.0 '4.1.0'

D:\xampp\htdocs\pvdata\testSelenium\test> npm view  mocha@5.* version

Where does npm install Global packages?

D:\xampp\htdocs\pvdata\wrapp\functionalTesting>  npm root -g 

List Global installed Modules

Listed a Certain Global Module 
D:\xampp\htdocs\pvdata\testSelenium\test> npm ls -g browserify
`-- browserify@15.2.0

Listed All Global Modules 
D:\xampp\htdocs\pvdata\testSelenium\test> npm ls -g | more
+-- browserify@15.2.0
| +-- assert@1.4.1
| | `-- util@0.10.3 deduped
| +-- browser-pack@6.0.3
| | +-- combine-source-map@0.8.0
| | | +-- convert-source-map@1.1.3
| | | +-- inline-source-map@0.6.2
| | | | `-- source-map@0.5.7 deduped
| | | +-- lodash.memoize@3.0.4
| | | `-- source-map@0.5.7
| | +-- defined@1.0.0 deduped
| | +-- JSONStream@1.3.2 deduped
| | +-- safe-buffer@5.1.1
| | +-- through2@2.0.3 deduped
| | `-- umd@3.0.1
| +-- browser-resolve@1.11.2

Install a certain module version

D:\xampp\htdocs\pv\WRApp\test> npm install selenium-webdriver@3.6.0
npm WARN saveError ENOENT: no such file or directory, open 'D:\xampp\htdocs\pv\WRApp\test\package.json'
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN enoent ENOENT: no such file or directory, open 'D:\xampp\htdocs\pv\WRApp\test\package.json'
npm WARN test No description
npm WARN test No repository field.
npm WARN test No README data
npm WARN test No license field.

+ selenium-webdriver@3.6.0
added 30 packages in 6.238s

List the top Level modules ONLY

D:\xampp\htdocs\pv\WRApp\test>npm  list  --depth=0
`-- selenium-webdriver@3.6.0

Un-Install a certain module

D:\xampp\htdocs\pvdata\testSelenium\test> npm -g list --depth=0
+-- eslint@4.14.0
+-- mocha@4.1.0
`-- selenium-webdriver@4.0.0-alpha.1

D:\xampp\htdocs\pvdata\testSelenium\test> npm uninstall -g selenium-webdriver
removed 30 packages in 4.04s

D:\xampp\htdocs\pvdata\testSelenium\test> npm -g list --depth=0
+-- eslint@4.14.0
`-- mocha@4.1.0


A Beginner’s Guide to npm

Running my first Node.js project with Netbeans


Node.js Overview

Node.js processing model

  • Follows single threaded even loop processing model which can handle more and more concurrent requests easily
  • Another important point to keep in mind that Node.js architecture has two types of threads

Main Thread (Single Thread)

  • Called as internal thread as well, all the non I/O blocking requests are assigned using Main thread

Worker Thread(s)

  • Used for assigning blocking I/O heavy requests

Here are the details on how the single threaded event loop based processing works

  • Client sends the request to web sever
  • Node.js web server receives client requests from different clients, puts them into a queue. This queue is called event queue
  • Node.js has an internal component called event loop which runs the loop on event queue, assigns the request to a single thread if the request is non-blocking
  • In case of blocking (I/O heavy) request, event loop will assign this to worker thread
  • While worker thread is processing the request, event loop will continue to process other requests available in event queue

Node.js and Standard Webserver Flow-Diagramms

Node.js Flow Diagram
Image nodejs_img1.jpg NOT Found
Standard Webserver Flow Diagram
Image nodejs_img2.jpg NOT Found

My First Node.js Web Application

How it works ?

  • Netbeans runs our Code in 2 Steps
  • Step1: Netbeans start a nodejs server process to execute HTTP server Code
  • –> Our HTTP server is now listening on port : 9900
  • Step2: Netbeans starts a Chrome Browser Windows and connects to Port 9900
  • –> Our Browser display the Content provided by our Http Server

Run a first Node.js Project

Setup a Node.js project properties within Netbeans

Step 1 : Configure Netbeans Project Run Methode Step 2 : Configure Node.js Properties
Image nodejs_img1.jpg NOT Found Image nodejs_img2.jpg NOT Found

Add the following Code to main.js

const http = require('http');
const port = 9900;

const requestHandler = (request, response) => {
    let funcName = "requestHandler";
    if (request.method === 'GET' && request.url === '/' ){
        dumpMessage(funcName, "Request Method: GET - request URL: " + request.url);
        response.writeHead(200, {"Content-Type": "text/html"});
        response.end('Hello Node.js Server - at:  ' + getTime() + '!');

const server = http.createServer(requestHandler);

server.listen(port, (err) => {
    let funcName = "server.listen";
    if (err) {
        return console.log(funcName, 'something bad happened: ' + err);

  dumpMessage(funcName, 'server is listening on port: ' + port);

function dumpMessage(testName, mesg) {                                       
    console.log(getTime() + testName + ":: --> " + mesg);           
function getTime() {
    var ts = new Date();
    return ts.toLocaleTimeString()+ ":" + ts.getMilliseconds() + "  ";

Finally run the Node.js Code

Step 3 : Run the project
Image nodejs_img3.jpg NOT Found

Run above Node.js project manaully

Start the http Server

D:\xampp\htdocs\pvdata\testNodejs> "D:\Program Files\nodejs\node.exe"  "D:\xampp\htdocs\pvdata\testNodejs\main.js"
17:14:42:536  server.listen:: --> server is listening on port: 9900

Redirect your browser to the Listening Adress of our Web Server: http://localhost:9900

Browser Output
Image nodejs_img4.jpg NOT Found

Debugging a Node.js Application with Netbeans – Currently NOT working due to Netbeans Bug 271238

"D:\Program Files\nodejs\node.exe" "--debug-brk=9292" "D:\xampp\htdocs\pvdata\testNodejs\main.js"
 (node:10116) [DEP0062] DeprecationWarning: `node --debug` and `node --debug-brk` are invalid. 
Please use `node --inspect` or `node --inspect-brk` instead. 


Debugging ourNode.js Application manually

Start the node.js process with inspect-brk option

  • Enable inspector agent
  • Listen on default address and port (
  • Break before user code starts
D:\xampp\htdocs\pvdata\testNodejs> node --inspect-brk main.js
Debugger listening on ws://
For help see

Attach Chrome Devtools 55+ to the Node.js Debugger process

  • Open a Chrome DevTool 55+ Browser session with following URL: chrome://inspect
  • Select : Open dedicated DevTools for Node
Attach Chrome DevTools to Node.js Inspector
Image nodejs_img50.jpg NOT Found

CLI should respond with: Debugger attached

D:\xampp\htdocs\pvdata\testNodejs> node --inspect-brk main.js
Debugger listening on ws://
For help see
Debugger attached.

Start Debugging

Debug Node.js by viewing Sources and setting Breakpoint
Image nodejs_img51.jpg NOT Found