Node Js Interview Questions and Answers for Experienced

Question: What is node.js?
Node.js is a software for scalable server-side and networking applications.
Node.js applications are written in JavaScript.
It can be run within the Node.js runtime on Mac OS X, Windows and Linux with no changes.

Question: In which language Node.js is written?
C,C++, javaScript.

Question: Who is creater of Node.js?
Ryan Dahl

Question: What is current stable version of Node.js?
6.6.0 Version / 15 September 2016.

Question: How node.js works?
Node.js works on a V8 environment, it is a virtual machine that utilizes JavaScript as its scripting language.

Question: From where we can download Node.js?
http://nodejs.org/download/

Question: What do you mean by the term I/O?
Input/Output

Question: What does event-driven programming?
In event-driven programming, flow of the program is determined by events.

Question: Where Node.js can be used?

Web applications ( especially real-time web apps )
Network applications
Distributed systems
General purpose application

Question: What is Advantage of Node.js?

Following are advantage of Node.js as compare to other web scripting.

Faster
More concurrency user
Asynchronous
Least blocks
Helps to build scalable network programs

Question: What are two different types of functions in Node.js?

Asynchronous
Synchronous

Question: What is Callback in node.js?
It is used to handle the multiple request.

Question: What tool and IDE is used for Node.js?

Atom
Nodeclipse Enide Studio
JetBrains WebStorm
JetBrains IntelliJ IDEA
Microsoft Visual Studio with TypeScript
NoFlo – flow-based programming environment integrated with GNOME APIs

Question: How to get Post Data in Node.js?

app.use(express.bodyParser());
app.post('/', function(request, response){
    console.log(request.body.user);
    
});

Question: How to make Post request in Node.js?

 var request = require('request');
request.post(
    'http://www.example.com/action',
    { form: { key: 'value' } },
    function (error, response, body) {
    if (!error && response.statusCode == 200) {
    console.log(body)
    }
    }
);

Question: What is callback hell?
Callback hell refers to heavily nested callbacks that have become unreadable

Question: How to handle the "Unhandled exceptions" in Node.js?
It can be caught at the "Process level" by attaching a handler for uncaughtException event.
Example:

process.on('uncaughtException', function(err) {
  console.log('Caught exception: ' + err);
});

Question: How to download image from Web?

#Include Important library
var fs = require('fs'),
request = require('request');

#Create a Download Function
var downloadImage = function(uri, filename, callback){
  request.head(uri, function(err, res, body){
    console.log('content-type:', res.headers['content-type']);
    console.log('content-length:', res.headers['content-length']);

    request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
  });
};

Use the function in following way:

downloadImage('https://www.google.com/images/srpr/logo3w.png', 'google.png', function(){
  console.log('image is downloaded');
});

Question: How to Remove directory which is not empty?

var rimraf = require('rimraf');
rimraf('/some/directory', function () {
 console.log('Directory is removed'); 
});

Web Technology Experts Notes

Tuesday, 30 December 2014